bigram

This is a table of type bigram and their frequencies. Use it to search & browse the list to learn more about your study carrel.

bigram	frequency
natural selection	3952
natural history	3003
per cent	2044
united states	1566
let us	1359
south america	1277
north america	1250
years ago	1250
specimens examined	1235
charles darwin	1204
one another	1183
total length	1011
upper parts	974
one side	943
hind foot	926
new york	925
type locality	903
two species	903
new zealand	871
new species	852
one day	838
nervous system	821
every one	817
many years	763
one species	761
sexual selection	757
well known	736
distinct species	730
mustela frenata	690
long time	669
de la	649
raymond hall	617
feet high	594
north american	581
dark brown	576
geographical distribution	573
lower animals	570
takes place	561
adult male	544
good deal	540
closely allied	532
organic beings	517
much less	513
different species	512
one specimen	500
will find	499
royal society	495
adult males	495
british columbia	492
present day	491
take place	490
almost every	484
first time	482
dipodomys ordii	477
many cases	475
large number	473
animal kingdom	467
first place	463
basilar length	460
geographic range	460
several times	448
closely related	443
new subspecies	443
short time	439
two years	437
every day	432
many species	427
years old	426
comparative anatomy	420
taken place	418
glacial period	416
animal life	407
vent length	403
british museum	400
domestic animals	399
japanese birds	399
one hand	398
mustela erminea	397
every part	393
british association	392
living things	392
allied species	391
will give	390
took place	388
great number	388
two kinds	387
greater part	387
present time	386
central america	385
adult female	385
much larger	384
one hundred	383
new mexico	382
kansas publications	381
total number	380
tympanic bulla	379
upper part	378
much like	378
uncle robert	378
several species	378
list japanese	377
two hundred	376
greater number	375
national museum	374
inches long	372
will see	368
two specimens	366
geological society	362
three years	361
old world	358
sierra de	357
long ago	356
costa rica	354
breeding season	351
higher animals	351
one time	351
shall find	350
hind feet	349
natural science	347
new world	346
zygomatic breadth	346
different parts	346
give rise	344
shall see	342
asa gray	341
kansas lawrence	341
great deal	339
del fuego	339
tympanic bullae	338
different kinds	336
widely different	335
three feet	335
external conditions	334
two sexes	330
central nervous	329
twenty years	329
next day	329
dear sir	327
see also	319
two feet	317
many others	316
thomomys bottae	315
second edition	314
tierra del	314
home range	314
tells us	312
hind legs	312
thousand years	306
individual variation	303
south american	303
feet long	303
large size	303
certain extent	302
much greater	300
dorsal surface	300
even though	300
three times	299
either side	299
alimentary canal	298
one may	298
four feet	298
many times	297
hundred feet	297
geographic variation	297
secondary sexual	297
first sight	296
ventral surface	296
anterior margin	296
every year	294
two distinct	290
living beings	290
nineteenth century	289
young birds	288
will take	283
lower part	281
great numbers	280
summer resident	280
three species	280
several years	279
zygomatic arches	279
never seen	277
organic world	276
thirty years	275
five years	273
fresh water	273
five feet	271
will make	271
auditory bullae	270
states national	270
one part	269
perforatus digiti	268
well developed	266
sexual characters	266
many parts	264
miles south	264
adult females	263
knox jones	263
west indies	262
rocky mountains	262
may also	261
three days	260
almost always	260
organic evolution	259
two subspecies	259
three hundred	258
new england	258
will come	256
one end	255
two groups	254
see measurements	254
san juan	252
give us	252
hundred years	251
like manner	251
wild animals	250
research station	250
may well	250
young ones	249
ten years	249
san antonio	249
acquired characters	249
changed conditions	249
pocket gophers	249
will appear	248
one thing	247
two forms	246
six feet	244
palau islands	244
linnean society	244
species may	244
upper incisors	244
various parts	244
large numbers	244
human race	242
may say	241
tell us	240
small size	240
lower jaw	240
important part	240
following letter	240
rudimentary organs	239
new guinea	239
something like	239
much better	238
next morning	238
thomomys talpoides	237
herbert spencer	236
whole body	236
sir charles	235
sir joseph	235
crown vo	235
great britain	234
domesticated animals	234
many thanks	232
first edition	232
almost entirely	230
two days	230
six inches	230
will show	229
one case	228
ever since	226
physical conditions	225
sexual differences	225
nothing else	225
new forms	225
direct action	224
oceanic islands	223
much smaller	222
miles north	221
will probably	221
young man	220
successive generations	220
living matter	220
three inches	219
will now	219
one point	218
know whether	218
various kinds	217
caroline islands	217
south africa	217
many kinds	217
see fig	217
human body	216
box turtles	215
spontaneous generation	214
may see	214
short distance	213
professor huxley	213
good hope	213
animal world	212
erasmus darwin	212
thousand feet	211
pocket gopher	211
dear hooker	211
fossil remains	210
four years	210
may perhaps	210
home ranges	208
two inches	207
geological record	207
one will	207
will never	206
fully developed	206
malay archipelago	205
interorbital breadth	203
make use	203
quite different	203
publications museum	203
cocoa research	203
close together	202
old age	202
de candolle	201
another species	200
long series	200
two great	200
upper surface	200
great part	199
will soon	199
living species	199
set forth	199
one might	199
scrub forest	199
will become	199
one sex	198
will always	197
present state	197
male testis	197
great many	196
one individual	195
sierra del	195
different forms	195
type specimen	195
right angles	194
sir john	194
doubt whether	193
kansas publ	193
scientific men	193
glacial epoch	193
captain fitz	193
still less	192
great importance	192
three weeks	192
hundred yards	192
go back	192
closely resemble	192
two months	192
geographic distribution	191
two different	191
long period	191
four inches	191
flexor perforatus	190
new edition	190
volume page	190
must also	190
collected essays	189
will go	189
south dakota	189
never saw	189
birds micronesia	189
greatest width	189
salt water	188
november th	187
natural size	187
little doubt	187
become extinct	187
molariform teeth	187
every species	186
may add	186
sydney anderson	186
feel sure	186
southern part	186
human embryo	185
years later	185
glen roy	185
namru party	185
old man	185
one great	184
single species	184
much longer	184
far away	184
organic matter	184
wide range	184
made use	183
vegetable kingdom	183
many instances	183
wild state	183
one place	183
hind limbs	183
one year	183
hundred miles	183
many animals	183
human beings	183
four hours	183
one half	182
first part	182
flowering plants	182
external measurements	182
human species	182
several parts	181
scientific memoirs	181
upper lip	181
sierra madre	179
one kind	179
carbonic acid	179
breeding schedule	179
large part	178
mariana islands	178
embryonic development	178
southwest pacific	178
april th	177
last chapter	177
upper jaw	177
also found	176
closely resembles	176
elementary species	175
charles lyell	175
take care	175
ten feet	175
forty years	175
three specimens	175
american museum	175
various species	175
dorsal view	174
field work	174
intermediate forms	174
late years	174
exactly like	173
even now	173
zapus hudsonius	173
four times	173
american species	173
great difficulty	172
many generations	172
small birds	172
long since	171
germinal layers	171
mesa verde	171
zapus princeps	170
right side	170
several days	170
birds southwest	170
del carmen	170
lawrence university	170
general rule	169
cultivated plants	169
kansas sci	169
history volume	168
greatest length	168
certain species	168
march th	168
last year	168
given rise	168
every thing	167
peculiar species	167
miles west	167
opposite side	167
de vries	167
buenos ayres	166
may become	166
first two	166
new conditions	165
fifty years	165
proximal end	164
great plains	164
sur les	164
northern parts	164
anthropoid apes	164
color pattern	164
many birds	164
far less	163
western washington	163
straight line	163
california publ	163
two parts	163
maxillary tooth	162
coral reefs	162
great distance	162
sorex vagrans	162
much obliged	162
bring forth	162
pure white	162
organic nature	162
great work	161
cranial measurements	161
pacific ocean	161
higher vertebrates	161
kansas printed	161
ground color	161
incisive foramina	161
every case	161
anterior part	160
specimen examined	160
many places	160
may th	160
just like	160
early period	160
early spring	160
history editors	160
naked eye	160
two small	159
one must	159
nature study	159
many ways	159
common resident	159
may take	159
brought forward	158
spinal cord	158
may find	158
one female	158
two miles	158
living organisms	158
three months	158
natural conditions	158
gives us	158
royal institution	158
look like	157
la plata	157
two large	157
miles east	157
existing species	157
least width	157
almost certainly	156
may conclude	156
subspecies recognized	156
old friend	156
two new	156
northern part	156
pacific coast	155
widely separated	155
organic forms	155
larger size	155
will say	155
highly developed	155
one single	154
much interested	154
one man	154
nearly every	154
west coast	154
pretty well	154
one morning	154
geoffroy st	154
bright colours	153
tailed weasel	153
human life	153
often found	153
five hundred	153
already mentioned	153
ground squirrel	153
northeastern washington	153
big blue	152
marlborough place	152
pale yellow	152
us now	152
twenty feet	152
every kind	152
show us	151
vegetable life	151
two sets	151
just now	151
vol vii	151
well adapted	151
mastoid breadth	151
quite distinct	150
dear darwin	150
shows us	150
often seen	150
several kinds	150
racial characters	150
organic life	150
british mus	150
gives rise	150
first appearance	149
literature cited	149
one way	149
ever seen	149
will often	149
long enough	149
now living	149
left side	149
higher forms	148
looks like	148
common transient	148
inorganic world	148
latter part	148
many different	148
joseph hooker	148
de tamaulipas	148
good reason	148
zoological society	148
least one	147
small number	147
reddish brown	147
living forms	147
sea level	146
extinct species	146
widely distributed	146
great interest	146
six months	146
anterior edge	146
field notes	146
whole subject	146
southern hemisphere	146
distal end	146
opposite sides	146
tertiary period	146
dear wallace	145
various forms	145
next year	145
much time	145
vertebral column	144
feet deep	144
ten days	144
great extent	144
sir william	143
taking place	143
cascade mountains	143
one occasion	143
quarterly journal	143
east indies	143
size medium	143
december th	143
zoological gardens	142
blue river	142
every now	142
torrid zone	142
must necessarily	142
northeastern kansas	142
ten thousand	142
holds good	142
know nothing	142
specimens taken	142
still greater	142
life history	141
part ii	141
northern hemisphere	141
von baer	141
already seen	141
seven years	141
large proportion	141
one instance	141
see figure	141
will also	140
digiti iii	140
come back	140
now see	140
two males	140
insect life	140
square miles	140
will generally	140
two sides	140
many things	140
darwinian theory	139
one foot	139
et seq	139
black spots	139
may now	139
many respects	139
professor owen	139
species will	139
throughout state	138
climbing plants	138
optic nerve	138
first pair	138
great variety	138
posterior part	138
kansas acad	138
years since	138
may infer	138
three miles	137
pale brown	137
high degree	137
great basin	137
connective tissue	137
may seem	137
may appear	136
individual differences	136
early stage	136
four species	136
two men	136
far north	135
inch long	135
marshall islands	135
million years	135
local fauna	135
winter pelage	135
und ber	135
anterior end	134
will send	134
digiti ii	134
little time	134
dry land	134
chapter iii	134
june th	134
rocky mountain	134
chapter ii	134
may call	134
dare say	134
good fortune	134
may easily	133
blue mountains	133
recent years	133
whole world	133
fairly common	133
two pairs	133
artificial selection	133
gave rise	133
vol vi	133
never heard	133
national park	132
open air	132
one form	132
cloth extra	132
volume ii	132
arctic regions	131
every direction	131
told us	131
posterior surfaces	131
rio negro	131
feet elevation	131
lateral line	131
throughout life	130
came back	130
great majority	130
early stages	130
many plants	130
male male	130
food habits	130
good many	130
may therefore	130
two thousand	130
natural beauty	130
green leaves	130
lateral view	129
among animals	129
additional records	129
prairie vole	129
reproductive organs	129
strongly marked	129
will tell	129
creamy white	129
selection will	129
caudal appendages	129
tepalcatepec valley	129
eight feet	129
enable us	128
anything like	128
little bird	128
whole length	128
chapter iv	128
osmotic pressure	128
printer topeka	128
state printer	128
somewhat different	128
slightly larger	128
first year	127
various ways	127
last two	127
specific characters	127
now known	127
four hundred	127
lead us	127
san josecito	127
may possibly	126
eight years	126
young men	126
santa cruz	126
whole surface	126
evolution theory	126
two individuals	126
little way	126
highest degree	126
slightly different	126
general appearance	126
totally different	126
foramen ovale	126
question whether	126
shallow water	126
wild species	126
san luis	125
common ancestor	125
must look	125
far distant	125
doubtful whether	125
strong enough	125
tail feathers	125
brown colour	125
must take	125
best known	125
past history	125
different races	125
black tip	125
cranial characters	125
around us	124
dry season	124
many individuals	124
see whether	124
anything else	124
february th	124
small mammals	124
long periods	124
six years	124
upper side	124
eastern kansas	124
far back	124
smaller size	123
say nothing	123
great quantity	123
five inches	123
summer pelage	123
dorsal fin	123
unless otherwise	123
microtus pennsylvanicus	123
two hours	123
september th	123
allied forms	123
lower lip	123
living body	123
many points	122
volcanic islands	122
far greater	122
seminal liquor	122
somewhat similar	122
mental powers	122
living organism	122
fossil fishes	122
will produce	122
one leg	122
may occur	122
certain parts	122
extreme measurements	122
early part	122
five miles	121
primitive mouth	121
six weeks	121
much higher	121
posterior edge	121
vol iv	121
put forward	121
four days	121
may often	121
long tail	121
flexor cruris	120
far beyond	120
shall never	120
also called	120
small part	120
two genera	120
see letter	120
nearly equal	120
different conditions	120
reproductive system	120
domestic races	120
tail length	120
will remain	120
physiological units	120
great pleasure	120
five minutes	120
close interbreeding	119
almost like	119
great mass	119
first step	119
miles away	119
almost wholly	118
columbia river	118
eighteenth century	118
great difference	118
living creatures	118
vast number	118
white spots	118
great advantage	118
oak forest	117
following year	117
et al	117
ten minutes	117
large enough	117
january th	117
mexican plateau	117
madre oriental	117
little creatures	117
indian ocean	116
scientific work	116
will sometimes	116
geological time	116
every time	116
second time	116
must go	116
douglas county	116
large extent	116
small animals	116
alveolar length	116
general laws	116
first appeared	116
latter case	116
metatarsal tubercle	116
must always	116
one direction	116
des cygnes	116
marais des	116
carbon dioxide	115
first three	115
considerable number	115
slight differences	115
human mind	115
several hundred	115
solar system	115
new varieties	115
plastral length	115
interorbital region	115
certain amount	115
medullary tube	115
posterior margin	114
looked like	114
lower end	114
one group	114
rainy season	114
two females	114
without doubt	114
incisive foramen	114
later years	114
every side	114
columbian plateau	114
primitive gut	114
study pub	114
th edition	114
somewhat like	114
channel catfish	114
miles distant	113
bell vireo	113
human nature	113
ventral surfaces	113
upper molar	113
within reach	113
posterior end	113
put together	113
small quantity	113
old ones	113
first one	113
natural system	113
peromyscus maniculatus	113
physical science	113
miles southwest	113
long intervals	112
slight degree	112
whole series	112
red squirrel	112
eight inches	112
every animal	112
second place	112
may come	112
sandwich islands	112
three thousand	112
river drainage	112
carried away	112
one else	112
one knows	111
jermyn street	111
large amount	111
organic remains	111
los angeles	111
thirty feet	111
may give	111
found among	111
falkland islands	111
different degrees	110
chapter vi	110
alpine plants	110
every step	110
remarkable fact	110
birds british	110
southern parts	110
meadow mouse	110
old continent	110
living thing	110
fitz roy	110
great changes	110
cratogeomys castanops	109
might easily	109
san francisco	109
may even	109
equally well	109
must therefore	109
one spot	109
modified descendants	108
salt lake	108
july th	108
eastern washington	108
excretory organs	108
every respect	108
lower parts	108
great length	108
sexual difference	108
hundred thousand	108
neosho station	108
time ago	108
every way	108
many varieties	107
two young	107
canine teeth	107
point barrow	107
little distance	107
might well	107
entirely different	107
may safely	107
man may	107
de las	107
resembles adult	107
breadth less	107
sur la	107
become modified	107
without much	107
early morning	107
leads us	107
five days	107
sierra nevada	107
brought together	106
general law	106
far south	106
least two	106
certain degree	106
ventral side	106
october th	106
two others	106
representative species	106
almost invariably	106
san pedro	106
canary islands	106
many persons	105
every man	105
common sense	105
one mile	105
maximum width	105
five times	105
first principles	105
early age	105
four miles	105
josecito cave	105
seen one	105
next generation	105
two varieties	105
bright yellow	105
highly probable	105
transverse section	105
greatest number	105
wild boar	105
wild flowers	105
plant life	105
miles long	105
microtus montanus	105
given us	105
considerable time	104
several generations	104
young one	104
animal forms	104
chapter vii	104
large quantities	104
common origin	104
months old	104
upper end	104
toward tip	104
vol iii	104
certain number	104
slightly smaller	104
modern science	103
pocket mouse	103
last century	103
much pleased	103
well worth	103
western part	103
blue sky	103
saw one	103
list birds	103
temperate zone	103
living bodies	103
different ways	103
dead leaves	103
will get	103
marine animals	103
will serve	103
extensor iliotibialis	102
curious fact	102
us see	102
must suppose	102
little creature	102
south kensington	102
central part	102
many people	102
days later	102
may feel	102
native country	101
almost exclusively	101
relatively small	101
two birds	101
white flowers	101
original description	101
natural species	101
last night	101
mississippi river	101
two cases	101
much difficulty	101
specifically distinct	101
pterygoid fossae	101
bird life	101
new continent	101
special creation	101
early summer	101
one large	101
may make	101
get rid	100
small portion	100
field mus	100
geographic ranges	100
see life	100
deep water	100
dear old	100
less degree	100
one inch	100
dark stripes	100
one small	100
four specimens	100
physical geography	100
seems probable	100
red colour	100
different times	100
second year	100
distinct genera	99
common species	99
single cell	99
slightly darker	99
almost impossible	99
latitude degrees	99
may suppose	99
avium australasianarum	99
may mention	99
natural causes	99
relatively large	99
common stock	99
several occasions	99
hard work	99
still another	98
digiti iv	98
may sometimes	98
will tend	98
american book	98
lateral surface	98
american weasels	98
every individual	98
direct evidence	98
mental faculties	98
bahia blanca	98
little book	98
big caney	98
marginal records	98
never found	98
san carlos	98
river basin	98
nearly like	98
galapagos archipelago	97
two things	97
century ago	97
two animals	97
still remains	97
ten inches	97
tropical america	97
two classes	97
colorado river	97
similar manner	97
food supply	97
approximately feet	97
apple tree	97
species belonging	97
biological surveys	97
two points	97
mountain ranges	97
book company	97
lateral eyes	97
american continent	97
now let	97
whole group	97
always found	97
different animals	97
green colour	96
now found	96
better adapted	96
reader will	96
will continue	96
study area	96
organic particles	96
marine shells	96
yet another	96
original number	96
great care	96
external influences	96
fairly well	96
common progenitor	96
final causes	96
history reservation	96
will think	95
commonly called	95
almost certain	95
kansas museum	95
upper molars	95
exact locality	95
another kind	95
modal date	95
arkansas river	95
edition ii	95
five species	95
first day	95
pacific lowlands	95
two types	95
will grow	94
eyed vireo	94
equal numbers	94
southeastern washington	94
surveys collection	94
river valley	94
last letter	94
many thousands	94
scientific world	94
much trouble	94
new characters	94
living creature	94
primary forest	94
five toes	94
rio de	94
one night	94
observations made	94
fifteen years	94
basal margin	94
nearly allied	93
natural sciences	93
size small	93
female birds	93
quite possible	93
dear mr	93
great abundance	93
ever saw	93
puget sound	93
adult size	93
west indian	93
will ever	93
condylobasal length	93
brightly coloured	93
two races	93
great quantities	93
less inflated	93
white stripe	93
closely resembling	93
darwin wrote	93
differ much	93
pale green	92
numbers will	92
ticul alvarez	92
size large	92
progressive development	92
monte video	92
long hair	92
three different	92
feet thick	92
ten times	92
august th	92
long run	92
british isles	92
specific forms	92
posterior surface	92
hyla microcephala	92
highly variable	92
left behind	92
almost exactly	92
posterior border	92
little birds	92
particular species	92
hold good	92
little less	91
first week	91
shelled turtles	91
third edition	91
western north	91
lower side	91
far removed	91
chapter ix	91
bright red	91
digitorum longus	91
fifteen feet	91
various degrees	91
second volume	91
san gabriel	91
generic name	91
already stated	91
farther south	90
geological survey	90
small fish	90
species must	90
may still	90
differ greatly	90
many miles	90
living machine	90
sexual maturity	90
different climates	90
thyroid gland	90
feet away	90
temperate regions	90
remote period	90
last week	90
father wrote	90
two little	90
nearly similar	90
nearly straight	90
inner surface	90
one male	90
present condition	90
facial markings	90
closely similar	90
five specimens	90
three great	90
lower surface	90
every reason	89
wilson volume	89
farther north	89
nearly always	89
country people	89
great measure	89
present study	89
birds may	89
transition life	89
another part	89
wild creatures	89
winter resident	89
three kinds	89
quite agree	89
one bird	89
shore birds	89
per second	89
late pliocene	89
two weeks	89
seven feet	89
every living	89
deciduous forest	89
different individuals	89
single individual	89
clethrionomys gapperi	89
young trees	89
late summer	89
history review	88
absolutely necessary	88
per acre	88
much interest	88
plant world	88
must remember	88
small islands	88
body length	88
three pairs	88
vital force	88
six hundred	88
flint implements	88
little ones	88
last time	88
intermediate varieties	88
early days	88
many specimens	88
chapter viii	88
little boy	88
must come	88
lesser degree	88
see one	88
middle line	87
much shorter	87
biological science	87
size smaller	87
pale blue	87
two factors	87
living animals	87
genealogical tree	87
lower forms	87
yellow colour	87
santo domingo	87
greater degree	87
distinctive characters	87
brown spots	87
recent times	87
whole life	87
much used	87
less numerous	87
miles northwest	87
clear water	87
moral sense	87
look back	87
certain characters	87
full grown	87
whatever may	87
poor little	86
us suppose	86
several feet	86
jumping mouse	86
surrounding conditions	86
new form	86
black hair	86
first generation	86
might expect	86
great size	86
soon found	86
original form	86
cold weather	86
primitive man	86
louis agassiz	86
shall hereafter	86
careful study	86
many small	86
north wales	86
however much	86
reproductive cells	86
twenty miles	86
median eyes	86
jumping mice	86
larger number	86
south wales	86
blackening toward	86
male birds	86
white man	86
microtus ochrogaster	86
common parent	86
must give	85
breadth across	85
different groups	85
related species	85
history museum	85
asked uncle	85
young bird	85
must admit	85
dark stripe	85
return home	85
la guayra	85
osage orange	85
lateral processes	85
one adult	85
gradually blackening	85
caudal musculature	85
illustration illustration	85
internal structure	85
cape de	85
three distinct	84
weighed grams	84
day long	84
close resemblance	84
fossil bones	84
east wind	84
double flowers	84
scarcely ever	84
one common	84
open sea	84
period may	84
must now	84
found also	84
ferd voiland	84
germ plasm	84
single specimen	84
unconscious selection	84
will keep	84
distinct races	84
elk river	84
forty feet	84
males alone	84
new jersey	84
bright green	84
slight changes	84
run wild	84
measurement taken	84
human races	84
different countries	84
arid tropical	84
concluding remarks	84
green plants	84
porto santo	83
opposite direction	83
now know	83
perforans et	83
ten miles	83
whole country	83
organized beings	83
one pair	83
coastal plain	83
solomon islands	83
another way	83
first cirrus	83
put forth	83
considerable distance	83
ciudad victoria	83
nowhere else	83
des sciences	83
lower molars	83
approximately miles	83
standard length	83
vegetable matter	83
papers mus	83
dark green	83
work done	83
san diego	83
slight variations	83
fifty feet	83
dear lyell	83
see origin	83
otherwise indicated	83
first glance	83
among birds	83
river near	83
soon became	83
late mr	83
great change	82
dark spots	82
led us	82
considerable amount	82
us take	82
reithrodontomys megalotis	82
fossil species	82
perhaps even	82
interorbital constriction	82
higher degree	82
years afterwards	82
man must	82
galapagos islands	82
bishop mus	82
great height	82
make one	82
gave us	82
many forms	82
western kansas	82
three counterfolds	82
high mountains	82
first stage	82
adjacent islands	82
john lubbock	82
infinite number	82
somewhat less	82
may go	81
white spot	81
northeastern mexico	81
best adapted	81
different varieties	81
six specimens	81
recent period	81
occludent margin	81
quite sure	81
year round	81
many facts	81
philosophical transactions	81
basal length	81
new facts	81
inches high	81
meadow mice	81
nd edition	81
second part	81
small black	81
hardwood forest	81
first volume	81
time since	80
relatively short	80
parallel roads	80
time required	80
wood rat	80
better chance	80
antonio canyon	80
will cause	80
ray lankester	80
average size	80
ornate box	80
determine whether	80
widely spreading	80
fritz muller	80
presidential address	80
two lateral	80
ancestral form	80
per day	80
new variety	80
single pair	80
typographical errors	80
favourable variations	80
sometimes even	80
days ago	80
another instance	79
twelve feet	79
several specimens	79
sexual organs	79
mustela rixosa	79
cold water	79
subapical zone	79
philippine islands	79
breeding condition	79
ready recognition	79
lago de	79
almost equally	79
greatest part	79
new pocket	79
ground squirrels	79
never yet	79
mean temperature	79
et perforatus	79
professor weismann	79
exactly alike	79
young people	79
red sandstone	79
eastern united	79
passed away	79
still remain	79
byron leonard	79
one set	79
well made	79
tarsal fold	79
vol ii	79
three forms	79
may fairly	79
flexor perforans	79
three hours	79
every measurement	79
long distance	78
eastern part	78
washington acad	78
social instincts	78
wild life	78
interpterygoid space	78
whole question	78
general principles	78
recent species	78
shall now	78
west side	78
first appears	78
young plants	78
far better	78
may serve	78
throw light	78
may look	78
brought forth	78
eastern side	78
horned owl	78
physical forces	78
sagittal crest	78
one generation	78
philosophie zoologique	78
new spain	78
tropical scrub	78
juan de	78
feet wide	78
look forward	78
running water	77
tropical regions	77
pocket mice	77
proximal part	77
connected together	77
close relationship	77
one particular	77
help us	77
des plantes	77
greatest depth	77
another point	77
general character	77
little known	77
upper molariform	77
must say	77
following letters	77
domestic productions	77
demy vo	77
blood vessels	77
domestic varieties	77
la nature	77
much pleasure	77
papers bernice	77
vent lengths	77
entirely new	77
breeding span	77
much struck	77
single one	77
distal part	77
anterior surface	77
will suffice	77
many days	77
grayish brown	77
meade county	77
approximately one	77
vertebrate animals	77
first crosses	77
grouse creek	77
domestic breeds	77
wide open	77
geological periods	76
least interorbital	76
two main	76
fly away	76
neosho river	76
protective colouring	76
zygomatic arch	76
something else	76
known species	76
new genus	76
slightly less	76
found one	76
come across	76
every plant	76
another place	76
easily tamed	76
dark color	76
approximately equal	76
similar conditions	76
right hand	76
great distances	76
analogous cases	76
vast numbers	76
full species	76
pounds sterling	76
pine forest	76
several miles	76
first chapter	76
well enough	76
extinct animals	76
missouri river	75
though perhaps	75
now exist	75
inner metatarsal	75
one thousand	75
curious case	75
east side	75
giving rise	75
one third	75
almost universal	75
must needs	75
ancient times	75
small area	75
shall presently	75
true species	75
organic molecules	75
well established	75
small white	75
long line	75
like one	75
found two	75
may arise	75
analogous facts	75
important fact	75
second generation	75
plants may	75
new ones	75
two long	75
many insects	75
nocturnal migration	75
lower molar	74
will look	74
degrees minutes	74
resident throughout	74
large scale	74
occipitonasal length	74
quite another	74
new one	74
two halves	74
kansas natural	74
known range	74
late pleistocene	74
nearly half	74
francis darwin	74
among us	74
geological observations	74
will try	74
carnivorous animals	74
english sparrow	74
little later	74
mm long	74
average number	74
transitional forms	74
tibial nerve	74
following passage	74
well marked	74
ancestral forms	74
six days	74
several cases	74
less common	74
almost identical	74
first half	74
will bring	74
et de	73
winter months	73
two adult	73
must make	73
open country	73
geological succession	73
come within	73
darwin says	73
among others	73
medial surface	73
must first	73
darker color	73
like many	73
john burroughs	73
wood thrush	73
cheek teeth	73
pall mall	73
four months	73
favourable conditions	73
important factor	73
certain conditions	73
one parent	73
whole family	73
found near	73
one season	73
sexual dimorphism	73
nearly two	73
chapter xi	73
deer mice	73
closely connected	73
dorsal surfaces	73
natural laws	73
still living	73
des animaux	72
considerable extent	72
gray squirrel	72
quite clear	72
peculiar genera	72
later period	72
every possible	72
little girl	72
little fellow	72
old birds	72
every morning	72
large black	72
ruffed grouse	72
castor canadensis	72
even among	72
germinal layer	72
miles southeast	72
taxonomic status	72
certain cases	72
one nest	72
days old	72
upper neosho	72
hind wings	72
young male	72
peroneal nerve	72
existing forms	72
several others	72
santa rosa	72
brought back	72
thirty miles	72
full growth	72
white colour	72
one evening	72
species occur	72
good evidence	72
still higher	72
enables us	72
man will	72
middle america	72
greatly reduced	72
great value	72
great masses	72
give way	72
following day	72
relative size	71
european species	71
soft parts	71
heavy rain	71
vomerine sheath	71
elapsed since	71
additional specimens	71
red sea	71
perpetual snow	71
new bat	71
pygmy mice	71
last three	71
specific name	71
harvest mouse	71
much attention	71
lower mandible	71
extinct mammalia	71
pinkish buff	71
seven inches	71
song sparrow	71
well shown	71
vascular system	71
six miles	71
map showing	71
de janeiro	71
quarterly review	71
chemical forces	71
less distinct	71
one animal	71
whole animal	71
many new	71
small species	71
first thing	71
less well	71
physical features	71
several hours	71
one word	71
may represent	71
easily distinguished	71
months ago	71
two volumes	71
angeles county	71
external characters	70
half way	70
succeeding generations	70
doubted whether	70
miles northeast	70
inches deep	70
six species	70
olympic mountains	70
much farther	70
long neck	70
whole structure	70
land animals	70
old red	70
first discovered	70
never forget	70
kangaroo rats	70
chemical composition	70
best way	70
large animals	70
king county	70
quite impossible	70
pacific coastal	70
great class	70
sweet pea	70
may produce	70
gogebic lake	70
external appearance	70
dorsal stripe	70
among men	70
red clover	70
sexually mature	70
higher mammals	70
vocal organs	70
sixty years	70
thousand miles	70
take advantage	70
water fishes	70
relative position	70
sexual reproduction	70
wind blows	70
must confess	70
professor henslow	70
second pair	70
hardly ever	70
sixth cirrus	70
important point	69
mother carey	69
slightly concave	69
old one	69
harding county	69
flew away	69
just mentioned	69
see account	69
middle ages	69
will prove	69
twelve years	69
one little	69
hundred times	69
go away	69
animals may	69
two counterfolds	69
median process	69
north dakota	69
geomys bursarius	69
size larger	69
middorsal region	69
nearly related	69
living world	69
fossil shells	69
somatic muscles	69
young animals	69
see accounts	69
adductor muscle	69
south side	69
copley medal	69
comparatively recent	69
genus thomomys	69
much surprised	69
either sex	69
forest floor	69
north side	69
social life	69
interesting letter	69
little brown	69
southern africa	69
coxal glands	69
will follow	69
locality restricted	69
de los	69
little animal	69
wildlife service	69
sexual elements	69
several distinct	68
every word	68
good condition	68
sometimes called	68
first made	68
eighteen inches	68
outer edge	68
nearly three	68
quite new	68
worn away	68
small numbers	68
atlantic ocean	68
original type	68
washington publ	68
also made	68
may yet	68
new character	68
prosomatic appendages	68
much good	68
diamante pass	68
wild horses	68
direct line	68
san miguel	68
new life	68
selection may	68
kangaroo rat	68
desert slope	68
white pine	68
several places	68
baiomys taylori	68
central europe	68
text figures	68
lendell cockrum	68
biogenetic law	68
traps set	68
whole day	68
caney river	68
book will	68
alfred russel	68
average length	68
temperate climates	68
whole theory	68
somatic cells	67
one egg	67
vice versa	67
anal opening	67
mammary glands	67
living substance	67
quoin hill	67
mount rainier	67
anterior palatine	67
pano ayuctle	67
every single	67
will write	67
large series	67
specimens collected	67
first cause	67
nearly parallel	67
lower vertebrates	67
greatest breadth	67
perfectly fertile	67
might say	67
certain animals	67
certain plants	67
american indians	67
carefully examined	67
almost immediately	67
male sex	67
taken together	67
centuries ago	67
much later	67
chapter xii	67
one young	67
will therefore	67
breed true	67
get away	67
already described	67
dry leaves	67
measurements taken	67
lower jaws	67
three parts	67
generally known	67
verde national	67
different stages	67
marked varieties	67
long ages	67
greatly increased	67
resemble one	67
natural state	67
different types	67
black bear	67
harvest mice	67
every detail	67
corpora lutea	67
two separate	67
isidore geoffroy	66
southern states	66
louisiana state	66
stone wall	66
relatively long	66
brought home	66
snake river	66
eight miles	66
hardly know	66
different places	66
following extract	66
cape horn	66
upper sonoran	66
one plant	66
may obtain	66
life may	66
way back	66
downy woodpecker	66
whole process	66
germinal selection	66
hundred species	66
large areas	66
red deer	66
alta verapaz	66
see page	66
direct influence	66
smilisca baudini	66
make us	66
starting point	66
first appear	66
kaolak river	66
many hundreds	66
three subspecies	66
probably due	66
greater extent	66
seventeenth century	66
el salvador	66
know anything	66
later date	65
middle part	65
another case	65
one long	65
philosophical society	65
jenner weir	65
chief part	65
yellow fever	65
lined skink	65
may think	65
honey locust	65
three males	65
without exception	65
modern times	65
find one	65
old days	65
extensor iliofibularis	65
light brown	65
gradual development	65
inter se	65
geographical changes	65
general description	65
full development	65
next chapter	65
foramen magnum	65
shall soon	65
glacial action	65
shall give	65
great classes	65
one sees	65
will understand	65
continued selection	65
generally speaking	65
female female	65
york state	65
deciduous trees	65
even greater	65
fresh air	65
inferior angle	65
comparatively small	65
two plants	65
fluctuating variability	65
four young	65
smaller ones	64
eumeces fasciatus	64
just finished	64
geological history	64
eight days	64
numerous species	64
garter snake	64
one tree	64
subarticular tubercles	64
mourning dove	64
el sabino	64
white line	64
pacific islands	64
will perhaps	64
lofty mountains	64
weeks old	64
now generally	64
yards away	64
one type	64
might perhaps	64
volcanic rocks	64
maxillary teeth	64
posterior cirri	64
prater canyon	64
special sense	64
common descent	64
several weeks	64
thousand times	64
nine inches	64
sexual cells	64
former times	64
iliotibialis lateralis	64
postorbital breadth	64
now become	64
southern el	64
various animals	64
osmotic growth	64
basal segments	64
living animal	64
new forest	64
eight hundred	64
information concerning	64
pseudemys scripta	63
far enough	63
water plants	63
already referred	63
large females	63
interesting facts	63
old woman	63
two heads	63
geological changes	63
species now	63
indian islands	63
great service	63
orbitonasal length	63
moving bodies	63
body temperatures	63
extinct forms	63
argus pheasant	63
insectivorous plants	63
one class	63
lateral profile	63
ancestral stock	63
us look	63
vocal sac	63
geological period	63
vital phenomena	63
foot long	63
deer mouse	63
myotis evotis	63
occur together	63
relatively narrow	63
sudden appearance	63
damm farm	63
jardin des	63
two eggs	63
little attention	63
peromyscus boylii	63
fifty yards	63
professor haeckel	63
highest point	63
slightly modified	63
gabriel mountains	63
scientific investigation	63
inherited effects	63
least weasel	63
angle formed	63
contents page	63
averages per	63
letter refers	63
may result	63
lowest forms	63
may prove	63
either case	63
kilometers west	63
saw two	63
well acquainted	63
entomological society	63
see mr	63
south sea	63
man alone	63
new south	63
sylvilagus floridanus	63
incident forces	63
russel wallace	63
cruris lateralis	63
reciprocal crosses	63
fore legs	63
well aware	63
trionyx spinifer	62
trigeminal nerve	62
second cirrus	62
thickly clothed	62
numerical proportion	62
third day	62
long course	62
terrestrial animals	62
two rows	62
lost sight	62
average depth	62
floating ice	62
nine months	62
entire length	62
two countries	62
auditory meatus	62
will still	62
flexor digitorum	62
hollow trees	62
baton rouge	62
looking back	62
though still	62
different classes	62
heavy rains	62
will turn	62
exactly similar	62
whole groups	62
two layers	62
erminea richardsonii	62
still farther	62
successive variations	62
rock springs	62
inner side	62
young specimens	62
often used	62
yellow flowers	62
one eye	62
much esteemed	62
see nothing	62
birds world	62
selection theory	62
whole year	62
branchial segments	62
brilliantly coloured	62
almost universally	62
two primary	62
san fernando	62
scarcely possible	62
large flocks	62
breeding males	62
us consider	62
gastrocnemius pars	62
large portion	62
three young	62
incipient species	62
perfectly well	62
separate species	62
one genus	62
may use	62
without seeing	62
chemical compounds	62
good enough	62
pretty little	62
ascertain whether	62
long way	62
short period	62
small amount	62
another time	62
female sex	62
now existing	62
caudal fin	62
grows wild	61
either parent	61
become established	61
two ways	61
coloured plates	61
pars interna	61
relative abundance	61
working men	61
thrown away	61
whole system	61
single plant	61
one sense	61
year old	61
certain kinds	61
parent form	61
middle american	61
skull smaller	61
least three	61
school board	61
long letter	61
now turn	61
molar teeth	61
little blue	61
hollow tree	61
different islands	61
wholly different	61
shall make	61
lateral edge	61
climatic conditions	61
now come	61
four thousand	61
will allow	61
stratified rocks	61
specific gravity	61
much alike	61
many curious	61
front feet	61
black colour	61
two families	61
specimen taken	61
general form	61
natural enemies	61
sixteenth century	61
less conspicuous	61
made many	61
fruit trees	61
highest importance	61
primaries ensheathed	61
length less	61
wood rats	60
less important	60
physical causes	60
place among	60
carrillo puerto	60
far west	60
external auditory	60
felipe carrillo	60
erratic blocks	60
one variety	60
hind leg	60
easily seen	60
already given	60
immature plumage	60
slight modifications	60
upper edge	60
short tail	60
left hand	60
rancho pano	60
quite certain	60
contemporary review	60
times greatest	60
tertiary deposits	60
anterior half	60
longitudinal section	60
carnegie inst	60
boiling water	60
first instance	60
present work	60
organized bodies	60
blue jay	60
east indian	60
farther back	60
general way	60
rapid growth	60
will eat	60
brown leghorn	60
central american	60
six times	60
blue colour	60
general public	60
east coast	60
physical basis	60
chapter xiii	59
whole mass	59
miles wide	59
several varieties	59
sayal brown	59
better fitted	59
little billee	59
brilliant colours	59
natural law	59
various groups	59
looking like	59
intermediate links	59
forest trees	59
shall ever	59
new series	59
anterior ramus	59
like animals	59
might become	59
first thought	59
form one	59
square feet	59
glacial epochs	59
always present	59
sometimes found	59
invertebrate animals	59
good luck	59
postauricular patches	59
wild birds	59
successive changes	59
everything else	59
kansas river	59
miocene period	59
three centuries	59
singular fact	59
north carolina	59
great rivers	59
yellowish tan	59
flying squirrel	59
different habits	59
atlantic coast	59
large genera	59
still others	59
new races	59
species found	59
see table	59
single instance	59
original stock	59
every night	59
canal zone	59
clearly see	59
highly organised	59
branchial region	59
several points	59
two cells	59
cinnamon buff	59
will help	59
morphological characters	59
la marina	59
soto la	59
every branch	59
successive stages	58
sir james	58
well remember	58
vegetable world	58
brought us	58
much lower	58