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ILLINOIS BIOLOGICAL 
MONOGRAPHS 


VOLUME XVI 


PUBLISHED BY THE UNIVERSITY OF ILLINOIS 


URBANA, ILLINOTS 


EDITORIAL COMMITTEE 


Joun Trropore Buci Moz 
Fred WiILBuR TANNER 


Harry Jones VAN CLEAVE 


TABLE Or CONTENTS 
Nos. 1-2. The Turtles of Illinois. By Arvin R. Cann. 


No. 3. The Phylogeny of the Hemiptera, Based on a Study of the Head 
Capsule. By CHARLES STOCKMAN SPOONER. 


No. 4. A Classification of the Larvae and Puparia of the Syrphidae of 


Illinois, Exclusive of Aquatic Forms. By Exizapera M. 
HEIss. 


;eUh YOR 


ILLINOIS BIOLOGICAL MONOGRAPHS 


Vol. XVI Nos. 1-2 


PUBLISHED BY THE UNIVERSITY OF ILLINOIS 
UNDER THE AUSPICES OF THE GRADUATE SCHOOL 
Urpana, ILLINOIS 


1937 


EDITORIAL COMMITTEE 


Joun THroporE BUCHHOLZ 
FreD WILBUR TANNER 
Har.ey JONES VAN CLEAVE 


UNIVERSITY 
OF ILLINOIS 


1000—8-37—9888 


THE TURTLES OF ILLINOIS 


WITH 31 PLATES, 20 MAPS, AND 
15 TEXT-FIGURES 


BY 
ALVIN R. CAHN 


CONTRIBUTION FROM THE ZOOLOGICAL LABORATORY OF THE 
UNIVERSITY OF ILLINOIS 
No. 492 


iN} 


” 


, 


ay eee? 


a 


PREFACE 


For a number of years the writer has had in mind the production 
of a monograph dealing with the turtles of Illinois, if for no other reason 
than the fact that they have, as a group, been much neglected throughout 
the middle west. In most herpetological literature of the region much 
space has been given to snakes, salamanders, and frogs, but turtles have 
received at best a mere mention, being passed off with the enumeration 
of a species or two in a given locality. This is perhaps due to the diffi- 
culty of capturing specimens, coupled with the uncertainty of identifying 
most species as they sit sunning themselves in security on a log in the 
-middle of a pond, and the very awkward problem of keeping such bulky 
> creatures once they are captured. I suspect, however, that it is also in 

part due to the fact that there is really very little literature available to 
the average student or field collector which will enable him to identify 
with ease and certainty a species once he catches it. Keys there are, but 
many are located in old publications not everywhere available; many are 
so highly technical as to require an advanced knowledge of comparative 
anatomy for their comprehension and use; others are too superficial and 
general to be of really practical value. It has been the writer’s plan, 
therefore, to present a paper dealing with the various species of turtles 
found within the boundaries of Illinois, this paper to include keys to the 
families, genera, and species—intelligible to readers who are not profes- 
sional herpetologists—together with a full discussion of the life history 
of each species so far as it is known. Such a discussion must also con- 
tain a detailed description of the adult and young, eggs, habits, economic 
importance, food habits, sex differentiation, and parasites, in order to 
approach completeness. One real drawback, as the writer sees it, to the 
ready identification of turtles, is the lack of adequate photographs that 
will in themselves be an aid (and not a handicap) in the determination 
of the identity of the species. To that end he has bent every effort to 
illustrate the present paper-with the best photographs he could obtain. 
All the illustrations are original and have been made especially for this 
monograph. The photographs are either from living specimens or from 
freshly preserved material, in the latter case photographed within an hour 
after killing so as to insure full color values. 

The writer has drawn freely upon available literature, as will be seen 
on consulting the bibliography. This bibliography has been arranged 
under several headings so as to make it of greater use to both the ama- 
teur and the professional student. 


6 ILLINOIS BIOLOGICAL MONOGRAPHS 


The Hlinois State Natural History Survey, under the direction of 
Dr. Theodore H. Frison, has placed at the writer's disposal its collections 
of Illinois turtles. Unfortunately, the original collection made by Profes- 
sor H. Garman in 1888 for the State Laboratory of Natural History has 
disappeared and hence has not been available for study. This has proved 
to be a serious handicap, for the writer has been unable to obtain speci- 
mens of several species listed by Garman from Illinois. To Dr. David 
H. Thompson and Mr. Francis D. Hunt, of the Natural History Survey, 
the writer expresses his appreciation for their assistance in procuring 
specimens for examination from various parts of Illinois, and to the com- 
mercial fishermen who have sent in many sacks and barrels full of live 
turtles for study, the writer owes in large measure the information con- 
cerning the geographical distribution within the state. During the sum- 
mer of 1931, Mr. Joe D. Combs, of the Zoology Department of the Uni- 
versity of Illinois, spent two months under the writer’s direction, on the 
Illinois River at Meredosia, collecting information on life histories and 
obtaining many interesting facts. 

To the many friends all over the country who submitted material for 
comparison and for study, and to the American Museum, the Field 
Museum, and the United States National Museum, the writer expresses 
his deep appreciation for all courtesies rendered. 


CONTENTS 


Illinois Topography and Hydrography . 
Historical Review . 


Key to the Families of Illinois Turtles . 
Key to the Family Chelydridae. 
Key to the Family Kinosternidae . 
Key to the Family Testudinidae 
Key to the Family Trionychidae 


Family Chelydridae 
Genus Macrochelys 
Macrochelys temminckii 
Genus Chelydra : 
Chelydra serpentina. 


Family Kinosternidae . 
Genus Sternotherus : 
Sternotherus odoratus . 
Genus Kinosternon : 
Kinosternon flavescens . P 
Kinosternon subrubrum Shenae 


Family Testudinidae . 

Genus Clemmys . 
Clemmys guttata 

Genus Emys 
Emys eau 

Genus Terrapene . 
Terrapene carolina eatin 
Terrapene ornata 

Genus Graptemys. é 
Graptemys geographica. 


Graptemys pseudogeographica pecudoveseraphica : 


Genus Chrysemys. 
The Chrysemys Pronten 
Chrysemys picta marginata 
Chrysemys picta bellii . 
Chrysemys picta dorsalis 
Genus Pseudemys. 
Pseudemys concinna . 
The Pseudemys elegans-troostii Belen: 
Pseudemys troostii . 
Melanistic Males 


Family Trionychidae . 
Genus Amyda. 
Amyda mutica 
Amyda spinifera. 


103 
105 
113 
122 
123 
129 
138 
145 
152 
152 
159 
160 
169 


175 
175 
176 
184 


CONTENTS (Concluded) 
Hypothetical List. .. Spee | ay ap ete ie en a Be oe ae ee 


Stemnotherus:carinatus 2) <9) 0) 9 ts ee sete oO 
Ghrysemyspicta. . 4. 9s ee, en ee LOD: 
Amydaferoxi; = = = |) « = “8 e) « 0 @ 0c ome enero 
Chrysemysitreleaset’ 3 3 8 ee ee ee eee 00 
Pseudemys hieroglyphica . . . . . . . . . . ... . 201 
Glemmysiinsculpta = =) @> yay ee ee cee e203 
Bibliography ©5 is 3 4s ee ee ee ee ee ee ee eS 
Illinois References’ % 2 3. 2 a @ =@ 9s. = ) & =e gees us Seem e208 
General References . . 5. ) s = «© 1s © «© «© s © «© “© ww ,« 1209 
References for Adjacent States. . . . . . . 2. ee ee ee 212 
References tor Synonymy <9 6 6 ew ee ge ee ss ee re 


Glossary: -z, 9.) 4. Gh hats Sue Go ee ee ee ee ee eee) 


ILLINOIS TOPOGRAPHY AND HYDROGRAPHY 


The state of Illinois occupies a unique position geographically in the 
United States, for within its borders many of the major faunal and floral 
features of the east and west, the north and south, join and to some ex- 
tent overlap or intergrade. Here representative species of the eastern 
forests and the western prairies, of the northern and southern forests, 
come together, and meet with the species of the sand dune region of Lake 
Michigan. Hence, as one might expect, the biota is varied and rich. 

Illinois is essentially a prairie state, but about 42 percent of its total 
area, or about fifteen million acres, is classified ecologically as having 
been originally deciduous forest of various types. This great forest, 
before being destroyed by man, covered most of the southern third of the 
state, as well as the northeastern section. Here roamed the white-tailed 
deer (Odocoileus virginianus), the black bear (Euarctos americanus), 
timber wolf (Canis lycaon), gray fox (Urocyon cinereoargenteus), and 
red fox (Vulpes fulva). The remaining region, approximately 58 
percent of the total area, was of parkland formation: grass prairies, 
with clumps of trees scattered through it. With the colonization of the 
state and its phenomenal growth in population, the forested region was 
reduced, until at present it is represented by less than 3,000,000 acres. 
With the deforestation came the cultivation of the land, and this was sub- 
sequently accompanied by drainage. The present biota is the product of 
these changes. Deforestation automatically and directly eliminated the 
larger species of forest animals, while the indirect effects of deforestation 
—cultivation and drainage—have had a profound influence upon the 
aquatic biota. The deforested land can no longer hold its original quota 
of water, and hence the run-off is rapid and sudden and spasmodic, re- 
sulting in floods and in a diminution of the volume of the rivers. There 
is no possible way in which we can with certainty reconstruct the original 
faunal distribution within the state, especially in respect to such a group 
as the turtles, but certain it is that the original distribution of animals 
was quite different from that which we see to-day. And it requires no 
prophet to predict that the future holds an even more profound change. 

Illinois is essentially a plain, gently rolling in places, in others flat. 
It is the lowest (average elevation 600 feet) of all the north-central 
states, lying in the middle of the great interior basin of the North Ameri- 
can continent, which is bounded on the east by the Appalachian and on 
the west by the Rocky Mountains. In general, the elevation decreases 
from north to south and from east to west, but this is in no sense a regu- 


10 ILLINOIS BIOLOGICAL MONOGRAPHS 


lar decline. The two essential features which interrupt the plain surface 
of the state are (1) the moraine features of the drift area, and (2) the 
rock ridges. 

The drift areas of Illinois are important in relation to the drainage 
basins of the state. The southern limit of the glacial drift within [linois 
lies at the foot of the Ozark uplift in the southern part of the state; 
from here is passes eastward into Indiana, and north and west to East St. 
Louis and Quincy. Thus the major portion of the state is covered with 
drift (the Ilinoian drift of the geologist), with a small area of driftless, 
non-glaciated country at the extreme southern tip and following up the 
Mississippi River valley to Quincy and up the Ohio River valley into 
Indiana, and a second, isolated area in the northwestern corner of the 
state. The northeastern quarter of the state has for its outstanding topo- 
graphic features a series of terminal moraines which mark the irregular 
southern limits of the Michigan lobe of the Labrador glacier, this region 
being covered with early Wisconsin drift. The narrow band along the 
shore of Lake Michigan is the Valparaiso moraine, late Wisconsin in 
origin. These morainic ridges were formed by the retreat of the ice sheet 
from the Shelbyville moraine and are separated by drift-covered basins 
which undoubtedly represent old lake beds. The slope of these ridges is 
gentle on the side that was away from the glacier (west and south) and 
much more abrupt on the side toward the ice (toward Lake Michigan). 
Thus the streams are found to flow through these basins, receiving as 
their tributaries smaller streams flowing down the gentle slopes of the 
moraines. Hence the drainage of this Wisconsin drift area flows mainly 
to the south and west. Over the Illinoian drift area the drainage is toward 
the Mississippi River, in a southwesterly direction. At the southwestern 
tip of Lake Michigan lies the Valparaiso moraine, the terminus of the 
late Wisconsin ice sheet; between this and Lake Michigan flow the Des 
Plaines, Calumet, and Chicago rivers, the last two flowing into Lake 
Michigan (originally at least), the former finding an outlet through the 
moraine at an ancient outlet of Lake Michigan known as the “old Chicago 
outlet.” 

There are but few places where the underlying rock rises above the 
superimposed drift, these being in the northwest corner, where the Ni- 
agara limestone breaks through to the surface and where there never 
was any glacial drift; the southern end of the state, where the Ozark 
uplift crosses the state; and places along the Mississippi River where the 
lower carboniferous limestones rise as the bluffs along the eastern shore 
of that river. The rivers are consequently flowing largely through areas 
of glacial drift, connecting very few lakes, and showing but little drop 


THE TURTLES OF ILLINOIS—CAHN 11 


per mile and normally but a sluggish current. The average rainfall of 
38.2 inches for the state affords under ordinary conditions a sufficient 
supply of water to the rivers. The unusual drought of 1930 left the lesser 
streams and smaller lakes almost destitute of water, and the larger rivers 
and lakes at a record low mark. 

That Illinois is well supplied with streams of all sizes is recognized 
by a glance at the accompanying map of the river systems of the state, 
and one cannot help being impressed by the dendritic pattern of these 
streams. While there are innumerable tiny creeks throughout Illinois, the 
drainage of the state falls into the basins of five main rivers and Lake 
Michigan. All five of the rivers empty either directly or indirectly into 
the Mississippi River; hence all of the state, excepting only the narrow 
belt between the Valparaiso moraine and Lake Michigan, lies in the 
drainage area of the Mississippi. Since these river systems are in many 
cases essential to the understanding of the distribution of certain species 
of turtles, they are listed here, together with their approximate drainage 
areas (data from Leverett). 


TasLe 1.—TuHE RIVER SysTEMs OF ILLINOIS, WITH THEIR APPROXIMATE 
DRAINAGE AREAS 


River system Square miles 
Mississippi River Drainage 
PROGKRiver: « corc dees «see aaves Vote wees 5,310* 
(Green: Rivet .tecs doe eae reiew sere 1,000 
Pecatonica River. acs selene eats 780* 
Kishwaukee River.............----- 1,644 
Den UimoisdR iver ccs auc etences cee aye sieve sees 24,940* 
Des Plaines River................-- 1750 
Kankakee Rivet: .2222 ses 6. + oi 4-5 2,160* 
OX RAVER 210.0524 6c.ccr © cise esa seater das ckeucio he 1,560* 
Vermilion Rivers. o: ac casece sees nee 1,320 
Mackinaw Rivéras.<.o6.-.+cseee eae 1,200 
SPOON RIVE. ceil g.eca.sie e sicress essvee ease 1,820 
Sangamon River................---- 5,590 
Salt? Greeley cic tec qace sje oa cies 3 1,940 
Grookedi@reek: 25. Nosed basihaees 6 1,350 
Matcoupin Creek..2 2.2 ccc ceee ccc: 1,000 
3; WaskaskiawRivers donc. gaces cece sense 6,000 
Ae Big Muddy ¢Riversincccvisuesee eevee eon sedne - 2,400 
5. Ohio River: 
WrabashwRiver. ce os cr cece ois sucess 8,890* 
Big Vermilion River.............. 1,400 
embarrass? Ray ere: erepetelede taste essere 2,400 
Little: Wabash Rivers. .s..40184 46 3,190 
SalinewRivers eo s.c acct aeeeine ede fe 2,000 
Cache River. .22 scc.cteeernintiecsainesrns 623 


*Exclusive of the drainage area outside the boundaries of Illinois. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


ERS OF ILLINOIS 


RE 1—THE Riv 


3Ul 


TEXT-FIC 


THE TURTLES OF ILLINOIS—CAHN 13 


Rock River.—The Rock River rises in Dodge County, Wisconsin, and 
drains ten large clear-water lakes in that state. It enters [linois in Win- 
nebago County, flowing with considerable current although its maximum 
gradient is only two feet per mile. Its banks are low in many places, 
at least on one side, for the river wanders across its valley, which has 
bluffs of a moderate height. 


GREEN River.—This river flows for a considerable distance through 
a channel cut in sand and gravel from the Wisconsin glacier. It is only 
about 93 miles in length. In its course it meanders through two large 
swamp areas, where it almost loses its identity as a stream and where 
it has practically no current, while at its headwaters it flows along with 
a drop of some 25 feet to the mile. Its banks are low and without bluffs. 

Pecatonica River.—This river enters Illinois in Stephenson County, 
coming from its source in Wisconsin, its entire course in the state lying 
in the Illinoian drift. It flows through rolling country, some of which is 
timber land and some prairie, with a drop of only about 6 inches to the 
mile, its banks largely of rich earth and low. 

KISHWAUKEE Rtiver.—This stream is formed by the union of two 
branches, each with a drop of about 3 feet per mile. Its water is quite 
clear as it flows through a rolling country, its banks timbered in some 
places, and in others of the prairie type. 

Ittinots River.—This is the largest river system in the state, and the 
river itself is the largest stream. It has a depth that varies to an extreme 
of approximately thirty feet. In many places it has cut its way through 
rock and presents beautiful high bluffs in consequence, indicating that 
in former years it probably had a considerably greater volume of water 
than it has now. Most of the course of the [linois was down an ancient 
river outlet of Lake Michigan, from which, however, it is now cut off, 
the water of that lake having in late Pleistocene time discharged into 
the Mississippi instead of into the St. Lawrence. It is bordered by a 
large flood plain, overflowing it in periods of high water, and by a second 
flood plain now above the reach of even the highest water, representing 
the flood plain of the river at the time it received the Lake Michigan 
discharge. Within this second bottom area there are, in some places, small 
lakes. The river flows through many swampy areas (overflow ponds) 
and has a very large population of turtles because of the favorable en- 
vironment. It is a slow river with an average drop over its entire length 
of but 3.2 inches per mile. It is rich in aquatic vegetation, which affords 
excellent shelter for its aquatic fauna. The upper reaches of the river 
were formerly polluted by the discharges of Chicago into it by way of 
the drainage canal, and here all normal river life was lacking. 


14 ILLINOIS BIOLOGICAL MONOGRAPHS 


Des PLatNes River.—This stream drains a narrow valley lying be- 
tween the moraines west of Lake Michigan, arising in Wisconsin. Its 
entire course lies within the late Wisconsin drift, and since this is charac- 
teristically a morainic region, many small lakes and marshes are found 
along its path. Its bed is, in consequence of the region through which it 
flows, largely sand and gravel. Its passage through the moraine which 
bounds it on the west is considered to be the old outlet of Lake Michigan 
during late Pleistocene time. 

KANKAKEE River.—This river has its origin in Indiana, where it 
flows through what is considered as a glacial lake bed, that of Lake 
Kankakee. Its valley is therefore quite level, the drop in the 240 miles 
lying in Indiana averaging less than 5 inches per mile. In Illinois it en- 
counters its limestone base and drops more precipitately at certain points 
due to this factor. Its bed is largely gravel and rock. 

Fox River.—This river rises in Waukesha County, Wisconsin, where 
it flows through the Wisconsin drift area, connecting a large series 
of beautiful clear-water lakes. In Illinois it continues its progress 
through the Wisconsin drift, to enter the Illinois River at Ottawa. Much 
of its drainage basin lies in morainic areas from which, however, many 
of the lakes have disappeared because of drainage and cultivation. It is 
stated that the volume of the river has fallen off at least 50 per cent due 
to this drainage and cultivation. The channel is therefore narrow and in 
some places has precipitous banks. It drops from 3 to 5 feet per mile. 


VERMILION River.—This is the Vermilion River that discharges in- 
to the Illinois, not into the Wabash. It rises in the moraines of Ford and 
Livingston counties. It has cut for itself a deep channel through parts 
of its course, with precipitous bluffs and cliffs overhanging the water. 
It drains no lakes or marshes and hence suffers much loss of water 
during dry seasons, 

Mackinaw River.—This stream rises in McLean County and flows 
southwest to enter the Illinois below Pekin. Since it starts high in the 
Bloomington moraine, we find that it drops 40 feet during its first mile, 
but then slows down to 3 feet per mile over most of its upper reaches. It 
flows through a very narrow channel, and since it has no marshes to take 
up its water, it is subject to great variation in times of either heavy rain 
or drought. It is considered to be the most variable stream in the state. 

Spoon River.—This river rises in Bureau County, and for a large 
part of its course it parallels the Hlinois River. It is a river with con- 
siderable current as it flows through a relatively narrow valley. In fact, 
its current is so much greater than that of the Illinois into which it emp- 
ties at Havana, that it has built up a considerable delta in the latter river. 
It, too, is subject to great variations in its water content. 


THE TURTLES OF ILLINOIS—CAHN 15 


SANGAMON River.—This stream is reported to have the largest water- 
shed of any of the tributaries of the Illinois River. The first part of its 
course traverses the early Wisconsin drift, which it leaves near Decatur. 
Beyond this point it is considerably wider and shallower. It is subject to 
overflow in rainy seasons, the twelve-foot embankments not acting as a 
barrier at such times. Its main tributary is Salt Creek, which rises from 
two heads, the North and South Forks; both have their origin in the 
Bloomington moraine. The Sangamon has considerable current, as the 
gradient increases to 10 feet per mile at its mouth. 

CrookEeD CrEEK.—This is the last tributary of any size of the Illinois 
on the western side. It flows entirely through Illinoian drift and has a 
channel which in places is bounded by high bluffs with limestone outcrops 
at intervals all along its course. 

MacouPin Creek.—This flows through a broad valley of Illinoian 
drift, almost level, with areas of heavy timber along its banks. These 
banks are largely of black soil, sometimes quite high, sometimes scarcely 
above the level of the river. 

Kaskaskia River.—This is one of the three rivers rising in the 
moraines of Champaign County (the other two being the Embarrass 
and the Sangamon). It rises in the area of the late Wisconsin drift, 
passing through the moraine near Shelbyville. The banks along its upper 
course are of mud but they become sandy downstream. It is a slow 
stream, its greatest drop being 3 feet to the mile, but through most of 
its course the drop is much less. Due to the nature of its flood plain, 
there is much timber along its valley. It has numerous tributaries, but 
these are all small. 

Bic Muppy River.—This is a very crooked river which shows evi- 
dence of being an old stream which has cut its channel down to drainage 
level, flowing through a flood plain which is broad and flat. It is slow 
and sluggish, dropping less than a foot a mile over most of its course. 
The water is very muddy for it carries much alluvial material. The last 
twenty miles of its course are through the Mississippi bottoms, and the 
backwater of the Mississippi is felt as far upstream as Murphysboro. In 
passing through these bottoms, the Big Muddy hugs the eastern shore, 
where bluffs 250 feet high bound its course on that side, the flat flood 
plain of the bottoms lying on the west. 

WapsasuH River.—For nearly 200 miles the Wabash forms the bound- 
ary between Illinois and Indiana, flowing through the pre-glacial bed of 
a river that at one time was much larger than the present stream. It is 
a sluggish, muddy river with a drop of less than 8 inches to the mile. Its 
valley is broad and low, and its bottom lands subject to severe overflows. 
It is shallow for its size, and numerous rocky rapids interrupt its other- 


16 ILLINOIS BIOLOGICAL MONOGRAPHS 


wise tranquil course. Its water is loaded with sediment in suspension— 
largely silt—so that it is brown and opaque at all times. 

Bic Vermition River.—The upper course of this river passes 
through a region deep in drift, through which it has cut a narrow course 
with relatively low banks. In the region of Danville, however, it has cut 
its way through the drift and flows between steep, high banks over a bed- 
rock course. Its water is fairly clear except in times of flood, and there 
is little vegetation in the lower reaches of its course. The upper portion, 
however, is shallow and weed-clogged, with water which is normally 
quite muddy. 

Emparrass River.—The original source of this river in Champaign 
County is now largely corn fields, but the river starts its course as a tiny 
weed-choked stream in the Champaign moraine system and Wisconsin 
drift. Emerging into the Illinoian drift, its valley broadens greatly as its 
rate of drop falls to less than 1 foot to the mile. There are few tribu- 
tary streams to the Embarrass as it flows through the relatively young 
Wisconsin drift, but in the older Illinoian area it receives many tribu- 
taries, presenting a typical dendritic system of drainage. 

Litrte WasasH River.—This river rises in the Shelbyville moraine 
and flows through the Hlinoian drift with an average drop of less than 
2 feet to the mile. Its valley is broad, with rolling hills and considerable 
heavy timber growing on the rich sandy loam which is subjected to heavy 
overflow in flood times. 

SALINE River.—This stream drains southeastern Hlinois which lies 
north of the Ozark uplift, entering the Ohio near Shawneetown, flowing 
through Illinoian drift. It is formed by the union of the North, South, 
and Middle Forks, beyond which point the Saline flows southeast along 
the base of the uplift. The river drops 35 feet in the 16 miles of its 
course. The southern banks are high, the northern relatively low, and the 
course is crooked and the current slight. 

CacHe River.—This is a small river which enters the Ohio at Mound 
City. It flows through the driftless area of the state, south of the Ozark 
uplift. Its course is through flat, alluvial material and cypress swamps, 
and its bottoms are subject to violent floods. It falls rapidly (150 feet) 
during the first 20 miles of its course, and but 50 feet in the remaining 
50 miles of its length. It is believed that the valley of the Cache River 
was once the main discharge channel of the Ohio River. 


HISTORICAL REVIEW 


When one reviews the literature dealing with the Testudinata, espe- 
cially in the United States, one is impressed by the lack of publications 
of monographic proportions; they are almost non-existent. By far the 


THE TURTLES OF ILLINOIS—CAHN 17 


greatest bulk of turtle literature is to be found in works of a general 
herpetological nature, as Harlan’s Genera of North American Reptilia 
(1826), Holbrook’s North American Herpetology (1836), Gray’s many 
publications, Van Denburgh’s Reptiles of the Pacific Coast, and innumer- 
able smaller papers. Agassiz’ monographic work (1857) on the turtles 
of the United States still remains the classic example of its kind, and has 
never been approached by any other publication for the wealth and 
originality of its contents and the value of its contributions. The other 
important and perhaps outstanding monographs are those of Surface 
(1908) on the economic status of the turtles of Pennsylvania, Babcock 
(1919) on the turtles of New England (which has the finest of colored 
plates), and Van Denburgh’s Gigantic Land Tortoises of the Galapagos 
Archipelago, with which we are not concerned in the present paper. 
There has been no monograph of the turtles of Illinois published. There 
is, in fact, no monograph in existence dealing comprehensively with the 
turtles of the middle west or of any state in the Union west of Penn- 
sylvania. There are numerous taxonomic and anatomical papers which 
the student must consult, and from the taxonomic series has grown the 
Stejneger and Barbour Check List (1933). Studies of the life histories 
of turtles are few and very far between, brief and usually very incom- 
plete in the information which they offer. The greater bulk of the turtle 
literature consists of scattered faunal notes of the occurrence of this or 
that species in a given circumscribed locality. 

Studies in the herpetology of Illinois have been few, and with the 
notable exception of Michigan, the same can truthfully be said of the 
surrounding states. This is exceedingly unfortunate, for we cannot but 
wish that the early herpetologists and general zoologists had left us a 
more complete record of the interesting herpetological information of 
their times than we find. The changes in the physical features of the 
state—deforestation, drainage, agriculture—must have left a profound 
impression on the amphibian and reptilian life of the region, and a study 
of these changes in relation to these animals would be most interesting 
and valuable, had we but the material or the data for study. 

The first Illinois list of turtles is included in a very general paper 
dealing with the animal life of Cook County, Illinois, published by Kenni- 
cott in 1855. This list records four species: Trionyx ferox, Cistuda 
blandingti, Chelonura serpentina, and Emys picta. It is interesting to 
note that two of these species are now considered invalid for the state 
(Trionyx ferox and Emys picta). The second list of the herpetology of 
the state is that of Davis and Rice (1883), listing eight species of turtles 
for the entire state, three of which are no longer valid. Harrison Gar- 
man’s first paper (1889), dealing with the animals of the Mississippi 
bottoms around Quincy, Illinois, lists nine species for that region; his 


18 ILLINOIS BIOLOGICAL MONOGRAPHS 


second paper (1890) adds three species to this number. The one and 
only comprehensive treatise on the herpetology of the state is the paper 
of Garman, published in 1892, in which he gives not only keys to the 
species, but a brief description of the forms, together with distributional 
notes and definite Illinois locality records. Garman’s work was done for 
the [linois State Laboratory of Natural History, and it is very unfortu- 
nate that all the specimens upon which this most important contribution 
was based have disappeared. Notes on Illinois species have appeared 
in many publications, and short lists of species found in various cir- 
cumscribed areas, such as Blanchard’s paper on southern Illinois (1924), 
Hankinson’s on the Charleston region (1915, 1917), and Weed’s notes 
from central Hlinois (1923), all of which are helpful contributions to 
a more complete knowledge of the amphibians and reptiles of the state. 

Since there is no monograph dealing with the turtles of the middle 
west, it is hoped that the present contribution, incomplete though it is 
in all its possible details, will fill for the time being a conspicuous gap. 
The nomenclature followed is substantially that of Stejneger and Bar- 
bour’s Check List of North American Amphibians and Reptiles (1933), 
from which the writer has departed only twice: (1) in the genus Chry- 
semys, in which group he feels that the data presented by Bishop and 
Schmidt (1931) warrant the adoption of their nomenclature for this 
group; and (2) in the problem of the Pseudemys troostu vs. Pseudemys 
‘elegans, in which data brought to light subsequent to 1933 have made a 
departure from their nomenclature apparently advisable. 

In order to bring before the reader the terminology as used in the 
present paper, with reference to the dermal and epidermal skeletal ele- 
ments of the carapace and plastron, the following outline is offered: 


1. Epidermal skeleton, composed of 2. Dermal skeleton, composed of bony 
scutes: plates: 
A. Carapace (Text-fig. 2) A. Carapace (Text-fig. 4) 
Vertebral Nuchal 
Costal Neural 
Marginal Costal 
Nuchal Marginal 
Caudal Pygal 
B. Plastron (Text-fig. 3) B. Plastron (Text-fig. 5) 
Gular Entoplastron 
Humeral Epiplastra 
Pectoral Hypoplastra 
Abdominal Hyoplastra 
Femoral Xiphiplastra 
Anal 
C. Bridge 
Axillary 


Inguinal 


THE TURTLES OF ILLINOIS—CAHN 19 


TEXT-FIGURE 2——The scutes compos- 
ing the epidermal skeleton of the cara- 
pace. C—costal; CM—caudal mar- 
ginal; M/—marginal; N—nuchal; V— 
vertebral. 


TEXT-FIGURE 4—The bony plates 
composing the dermal skeleton of the 
carapace of Pseudemys troostu. C— 
costal; M—marginal; Ne—neural; 
Nu—nuchal; P—pygal. 


TEXT-FIGURE 3.—The scutes compos- 
ing the epidermal skeleton of the plas- 
tron. A—abdominal; An—anal; Aa— 
axillary; CM—caudal marginal; F— 
femoral; G—gular; H—humeral; 
J—inguinal; M—marginal; P—pec- 
toral: 


TeExtT-FIGURE 5.—The bony plates 
composing the dermal skeleton of the 
plastron of Pseudemys troostu. En— 
endoplastron; Ep—epiplastra ; Ho—hy- 
oplastra; Hp—hypoplastra; Xi—Xiphi- 
plastra. 


20 


ILLINOIS BIOLOGICAL MONOGRAPHS 


KEYS TO THE TURTLES OF ILLINOIS 


The following keys are intended for the separation of the various 


species of turtles thus far reported from the state of Illinois. The charac- 
ters used are, in so far as possible, external, and the keys are so developed 
as to be an aid to the amateur as well as to the professional herpetologist. 
The use of osteological or cranial characters which necessitate careful 
dissection or tedious cleaning up of skeletal material has been avoided 
wherever possible. 


Si — 


(4) 


KEY TO THE FAMILIES OF TURTLES OF ILLINOIS 
Shell covered with horny epidermal shields.............0.00eeee eee (G23) 


Pectoral shields not in contact with the marginals, but widely sepa- 
rated from them; plastron with 11 shields or less............... 32) 
Plastron relatively very small, cruciform, composed of 9 shields 
besides the bridge; carapace flaring and emarginate posteriorly; 
no hinges present in plastron; head very large; tail long, with 
dorsal crest of tubercles; 25 marginals................0% CHELYDRIDAE 
Plastron larger, not cruciform, composed of 11 shields; 23 marginal 
shields, the carapace neither flaring nor emarginate posteriorly; 
symphysis of lower jaw a long, sharp point.......... KINOSTERNIDAE 
Pectoral shields in contact with the marginals; plastron with 12 
Shi SldS,. aise oreesehde ne ea come cite chee oaks ns Siate ek saree lanl meer eneReTe ‘TESTUDINIDAE 


Shell without horny shields, being covered with skin only. .TRIONYCHIDAE 


KEY TO THE FAMILY CHELYDRIDAE IN ILLINOIS 


No supramarginal shields; orbit directed upward and outward; head 
covered with skin; tail with two rows of large scales on the 
ventral surface; carapace with three ridges, becoming obsolete 
TE AC ULE yen ePaper erescesin ie nee sie eee Eee Chelydra_ serpentina 

Three or four supramarginal shields on each side just above the 
region of the bridge; orbit directed laterally; head covered with 
symmetrical plates; tail with many small scales on the ventral 
surface; carapace with three very strong, persistent ridges or 
GEIS) ccsictirecnve/adie «cpus opareraetgn rs e wiselel es aitays 2-0 tee lecerons Macrochelys temminckti 


KEY TO THE FAMILY KINOSTERNIDAE IN ILLINOIS 


Humeral scutes triangular; plastron quite large, nearly filling the 
aperture; little cartilage between plastral elements; lobes of 
plastron of approximately equal length....Genus Kinosternon. (2) 

Size large; carapace flat; ninth and tenth marginals elevated 
ae eres Rica ee ee oN ROSE Kinosternon flavescens 

Size small; carapace arched; only tenth marginal elevated.......... 
Shateustolaser oma adetaitare areata santo epiaeeear eee Kinosternon subrubrum subrubrum 


10 
11 


12 


13 


4 


15 


Gis) 


(6) 


(5) 


(6) 
(sy) 


(8) 


(13) 
(12) 


(11) 
(10) 
(7) 


(18) 


THE TURTLES OF ILLINOIS—CAHN 21 


Humeral scutes rhomboidal; plastron narrow, not nearly filling aper- 
ture; interpectoral suture about equal to interhumeral; posterior 
lobe of plastron longer than the anterior lobe, and truncate, the 
angles not rounded; much cartilage between the plastral ele- 
ATICTIES erat cers deeicte: d: Hlapeva\ ones 4 forsee eiteveiisasls totes alee Genus Sternotherus. (5 ) 


Carapace without a vertebral keel in the adult and without imbri- 
cated scutes; head with lateral yellow stripe back of the eye 
RR er en Perensiae cose esi ciee hd ieysiayssiscsian Orava, As) eset ees o.exbcee Sternotherus odoratus 

Carapace with a vertebral keel and imbricated scutes; Yead without 
lateralestripesi es POLLeG mits oirshslalel slave gate silsnstervi1 Sternotherus carinatus 


KEY TO THE FAMILY TESTUDINIDAE IN ILLINOIS 


Blastronmewithetransyerseulim Ges pavern cis che cie:a\s eee cheats sue eles Aescteteys hence (e222) 
Beak hooked; shell high and convex; bridge rudimentary or absent; 
plastron with posterior notch; no bony temporal arch. Genus 
Merete p em ease eca eters src ete cue erttelatetexacia/a ay ateis-a e oie ale siernvers te ete arate haaiy bigie (3) 
Carapace with low vertebral keel; no trace of a bridge; posterior 
lobe of plastron broader than anterior; plastron hermetically 
closing the shell; median suture nearly straight, slightly if at all 
SITITI OLS apeetetee cy to oes cs cceianalterciehera, ais ereveistakers Terrapene carolina carolina 
Carapace without a trace of a vertebral keel; a rudimentary bridge 
present; plastron not hermetically closing the shell; both plastral 


lobes of approximately equal width................ Terrapene ornata 
Beak without hook; shell somewhat depressed; bridge narrow but 

distinct; a bony temporal arch présent.............. Emys blandingtt 
Plastron without ‘transverse hingesea. ccc she occ cee ce cee steams « (G79) 
Carapace without a vertebral keel.........° ORR ar ees ree (8) 


Carapace relatively high, globular, the lateral marginals practically 
vertical; axillaries and inguinals small and rudimentary; plastron 
widely but shallowly emarginate; carapace with round yellow 
OES srcceraccacs sie teaiels < v(0roicss ins ahe.e.6 0, alsiole.o argjeceieves (el oie iste’ Clemmys guttata 

Carapace much depressed, the lateral marginals about 45° with the 
vertical; plastron without ligamentous connection with the 
carapace; axillary and inguinal elements large; posterior margin 


of plastron truncate or very slightly emarginate................ 
BN esr terete ye raherefarae de tevoreus eval wis hala voris’ = Genus Chrysemys. (10) 
Plastron yellow or orange, with symmetrical dusky markings....... (11) 


Plastron with dusky central area, this not radiating out along the 
STILURES rarcrs heave So cu ieteids= prac Side Gepadesslvia, Seeseus cb aus Chrysemys picta marginata 


Plastron with symmetrical central markings covering most of it, 
Tadiating out alone the SutureSscsqaasueeecne ees Chrysemys picta belli 


Plastron yellow or orange, without dusky central markings; costal 
and vertebral shields alternating............ Chrysemys picta dorsalis 


Carapace with a vertebral keel; posterior margin of the plastron 
deeply sotched sa...o seve oes ates ccernelecete as toe Oe wcities: sienccciess eisiers (15) 


Keel tuberculate and conspicuous.............-- Genus Graptemys. (16) 


16 


17 


18 
19 


20 


21 
22 


23 


24 


(17) 


(16) 


(2) 


(a9) 


(4) 


(3) 


ILLINOIS BIOLOGICAL MONOGRAPHS 


A triangular or comma-shaped yellow spot behind the eye; second 
and third vertebral scutes convex before the tubercle; head 
large; alveolar surface of jaws greatly expanded.............. 
sslae hada, by aa favsice fatelaydhalceyatayste Oe ateyel sear aierceeroropane seetaeas Graptemys geographica 

A boomerang-shaped yellow mark behind the eye, the median mar- 
gins of which parallel each other on the dorsal side of the head 
and neck; second and third vertebral scutes concave before the 
tubercle; head relatively small; iris pale...................2s00: 
aya kabiracd erdrSpavers te dev eveark Graptemys pseudogeographica pseudogeographica 

Keel Jow. and rudimentary. 2..-2-5e.- os. «cee se ase Seems a ateiee (19) 


Carapace highly sculptured, with a series of conspicuous concentric 
rugae on each scute................ Clemmys insculpta (hypothetical) 


Carapace not highly sculptured, without concentric rugae.......... 
cto %. dra iaapsvolOlane ea ovee imate cuake Pore aetilaloo ms sais eis chs HORS Genus Pseudemys. (21) 


Alveolar surface of both jaws with a smooth ridge...............4. (22) 


Carapace with conspicuous transverse yellow stripes; a blood-red 
longitudinal stripe back of the eye; carapace emarginate anter- 


iorly; plastron with a black spot on each scute................ 

sfonaial’s snes sina¥ havens Or sleye nase tiserarele Pseudemys troostii (formerly elegans) 
Carapace without yellow stripes; no blood red stripe behind the eye; 

plastron ‘with much. black mottling. «<<. .ccc.5c1e.sejeus ees ls tee 

ss aparece ete ere Svs Rters oe ee Pseudemys troostii (melanistic males) 
Alveolar surfaces of both jaws with a tuberculate ridge............. (25) 


Lower jaw with smooth cutting edge; shell greatly depressed; alveo- 
lar surface of upper jaw narrower at symphysis than on sides; 
outer surface of mandible arched; shell elongate, narrow........ 
Sarciplee Scale eaten i a ale e Shcote eve Pseudemys lieroglyphica (hypothetical) 
Lower jaw with serrate cutting edge; shell not greatly depressed; 
alveolar surface of upper jaw very wide all around; outer surface 
of mandible flat} shell broad. 2.2... 00.seie ss Pseudemys concinna 


KEY TO THE FAMILY TRIONYCHIDAE IN ILLINOIS 


Nostril circular, without a papilla projecting into it from the septum; 
snout very narrow, pointed; edge of upper jaw toothed poster- 
iorly; nuchal margin of the carapace without conical tubercles; 
under surface of feet white or grayish, not mottled....dmyda mutica 

Nostril crescent-shaped, with a papilla projecting into it from the 
septum; snout not so narrow and pointed, being but little longer 
than the diameter of the orbit; edge of upper jaw not toothed 
posteriorly; nuchal border of carapace with a row of conical 
spine-like. tuberclesisic.<.2:ssic.ccs10:0ie aveie-s s:s:ete cats s/s oveoic's o'staleveveccia’aisveie cle ete G3) 

Light stripes on head uniting at base of snout; an abundant species 
sie-b eis eI s WOuersiathnnkenana tre tree areacC Siatayate wisi eee re Ge Sieue eerege eaters Amyda_ spinifera 

Light stripes on head uniting just in front of the eyes; a rare or 
hypothetical species in southern Illinois only..................4. 
eT eee ane Pe ret eS ERD Amyda ferox (hypothetical) 


THE TURTLES OF ILLINOIS—CAHN 23 
FAMILY CHELYDRIDAE 


Emydidae (part) Gray 1825; 1855; Bell 1828 
Steganopodes (part) Wagler 1830 

Emydae (part) Gray 1831 

Elodites Cryptoderes (part) Dumeril & Bibron 1835 
Chelydroidae Agassiz 1857 

Chelydridae (part) Gray 1870; Cope 1872, 1882 


EXTERNAL CHARACTERS.—Shell covered with epidermal shields. Cara- 
pace relatively small, the posterior border serrated; 25 marginals. Plas- 
tron with nine shields, very small and not nearly covering the soft parts; 
cruciform. The abdominal scutes do not meet on the mid-ventral line, 
the articulation between the pectoral and femoral elements intervening, 
and they are further separated from the marginal scutes by a series 
of (usually two) inframarginals. Neck completely retractile within the 
shell. Head very large and massive and incompletely retractile within 
the shell; jaws strongly hooked. Digits moderately long, the claws four 
or five, the outer toes being clawless. Tail long, at least half the length 
of the carapace, and highly crested dorsally. Chin with paired barbels. 

OsTEOLocIcaAL CHARACTERS.—Temporal region incompletely roofed 
over; no parieto-squamosal arch present. Squamosal widely separated 
from the parietal. Cervical vertebrae: second and third opisthocoelous, 
the fourth amphycoelous; remaining procoelous. Caudal vertebrae: all 
oposthocoelous. Nuchal plate with very long costiform lateral processes 
extending ventral to the marginals. Pubic symphysis widely separated 
from the ischial. 


GeNus MacrocHELys GRAY 


Chelonura (part) Holbrook 1840 Gypochelys Agassiz 1857 
Macroclemys Gray 1855 Macroclemmys Strauch 1862 
Macrochelys Gray 1855; 1870 


Three or four supramarginal scutes interposed as extra plates be- 
tween the marginals and the costals in the region of the bridge; carapace 
with three keels which are very prominent as persistent ridges. Head 
very large and massive, often wider than long, and with large plates 
dorsally; orbits directed laterally. Alveolar surface of the jaws very 
broad; jaw very strongly hooked at symphysis. Tail with three series 
of dorsal tubercles and with many small scales ventrally. A_ single 
species is known; this is by far the largest of the fresh-water turtles, 
attaining a weight of over 200 pounds. 


24 ILLINOIS BIOLOGICAL MONOGRAPHS 


Macrochelys temminckii (Holbrook) 
(Alligator snapper ; loggerhead) 


Chelonura temminckti Holbrook 1840 Gypochelys lacertina Agassiz 1857 
Emysaurus temmincktt Duméril 1851 Macroclemmys temminckti Strauch 1862 
Macroclemys tenminckii Gray 1855 Macrochelys lacertina Cope 1872 


Macrochelys temminckii Gray 1855 


DescripTIon.—Carapace a wide oval, the width approximately two- 
thirds of the length; anterior margin practically smooth; posterior border 
with great tooth-like emarginations, these being associated largely with 
the posterior three marginals. Carapace with three great persistent 
ridges. The median keel is mid-dorsal down the middle of the vertebral 
scutes; it is present on each scute but becomes increasingly conspicuous 
toward the posterior end. On the last two vertebrals the keel arises from 
the anterior margin of the scute to a high, sharp posterior knob. The 
lateral keels lie along the dorsal medial edge of the costal scutes; these 
keels are, like the vertebral ridge, relatively low at the anterior end, and 
become increasingly prominent posteriorly. In the case of each costal 
scute the keel arises gradually from the anterior margin to a high, sharp 
posterior knob which drops abruptly to the edge of the scute. In many 
cases inconspicuous, low ridges tend to converge toward the tip of the 
knob. The first costal is roughly triangular; the remaining costals are 
rectangular. Three or four (rarely five) supramarginal scutes are located 
between the lateral margin of the anterior three costal scutes and the 
adjacent marginals; this is in the region of the bridge. Plastron small, 
narrow, cruciform, not nearly covering the soft parts. The plastral 
scutes are subject to great variation both in number and in relative 
position. All of the usual elements are present, but the abdominals are 
pushed out to form the major portion of the bridge, leaving the pectoral 
and femoral scutes in contact in the central area. Many small accessory 
scutes are interspersed throughout, and often there are one or two inter- 
gular scutes present. The head is enormously large and massive, the 
great masseter muscles building up a mound at the posterior region of the 


TEXT-FIGURE 6.—The skull of Macrochelys temminckit. 


THE TURTLES OF ILLINOIS—CAHN 25 


head from which the profile slopes in a concave curve to the protruding 
snout. The beak of the upper jaw projects far beyond the tip of the 
lower, and terminates in a sharp hook. The cutting edge of the upper 


Pate 1.—Macrochelys temmincku: A, Adult specimen weighing 103 pounds, 
dorsal view. B, Same individual, ventral view. C,+Newly hatched individual 
(Agassiz specimen, courtesy of the Museum of Comparative Zoology), dorsal view. 
D, Adult, lateral view. 


26 ILLINOIS BIOLOGICAL MONOGRAPHS 


PLATE 2.—Macrochelys temmincku; A, Head study of a large adult. B, Mouth 
of the same individual, opened to show the “worm” on the tongue. C, Detail 
study of the “worm” on the tongue. 


THE TURTLES OF ILLINOIS—CAHN 27 


jaw rises just posterior to the tip of the beak, to descend again posterior 
to the orbit and rise again toward the angle of the jaw, giving it a wavy 
contour. The lower jaw is also strongly hooked, with a uniformly curved, 
sickle-like cutting edge. The top of the head is covered with rather large, 
imbedded, symmetrical plates. Neck relatively short, stocky; the skin 
bears many dermal tentacles of various sizes, some quite large and very 
conspicuous. These tentacles also adorn the chin. The tail is very long, 
about two-thirds the length of the carapace, and bears on its dorsal 
surface three low rows of tubercles; the ventral surface is covered with 
small, rounded scales. Limbs strong and very powerful; feet large; 
claws very strongly developed. Skin on the ventral surface tuberculate. 


CoLoraTion.—Carapace dark brown, without any pattern and often 
covered with a thick growth of algae. Plastron a paler brown, also un- 
marked. Head, limbs, and tail dark brown, darker above than below. 
Head with inconspicuous darker brown spots which are usually quite 
indistinct. Iris black, with radiating brown or golden brown bars di- 
rected toward the pupil. 


Younc.—The newly hatched young of the alligator snapper are ex- 
tremely rare, and diligent search failed for a long time to reveal a single 
specimen in collections. At last, thanks to the kindness of Dr. Loveridge 
of the Museum of Comparative Zoology, the writer had the opportunity 
of examining and photographing the original specimen described by 
Agassiz (1857) and shown in the lithographs as figures 23-27, plate V, 
volume 2, of his work. The specimen is still in a perfect state of preser- 
vation. The newly hatched young exhibit all of the characteristics of the 
adult, reduced to miniature, and may be separated from the young of 
Chelydra serpentina by the same features. It differs from the adult in 
that the scutes of the carapace, especially the marginals, are greatly 
roughened by irregular corrugations and wart-like protuberances, and 
in the rather fancy, scroll-like formation of the first marginals. Further- 
more, the skin of the young is far more highly ornamented with barbels 
than in the adult, these fairly covering the surface. The body propor- 
tions of newly hatched young are more nearly like those of the adult than 
in most other species of turtles, though the tail.is relatively longer. 

Sex DIFFERENTIATION.—There is an insufficiency of material avail- 
able to warrant any generalizations on this subject, the two specimens 
which the writer handled both being females. 

GrEoGRAPHIC DrstripuTION.—The range of the alligator snapper is 
limited to the Mississippi River and its larger tributaries, and to a few 
other rivers flowing into the Gulf of Mexico from Texas to northeastern 
Florida. So far as the writer is aware, Quincy, Illinois, is the most 
northerly record of the species in the Mississippi, and it is very rare this 


28 ILLINOIS BIOLOGICAL MONOGRAPHS 


far north. It is a southern species, still rather common in the lower 
Mississippi River from central Arkansas to above the delta region of 
Louisiana; Hurter (1911) reports it from several localities in Missouri, 
but it is increasingly rare from central Missouri northward. One record 
outside of this circumscribed area occurs in Yarrow’s Check-list (1882) ; 
here he records two specimens, U. S. N. M. #12345 from Northville, 
Michigan. A check on these specimens by Dr. Stejneger shows them to 
be incorrect. The National Museum never had any specimens of this 
turtle from Michigan, nor is any turtle listed under the number 12345. 
Itt1No1s Recorps.—There are but a few records of this huge turtle 
for Illinois, and it must be considered as a rare species within the state, 
for such a large animal is more than likely to attract attention if present 
in any numbers. Dr. H. Garman (1892) reports it from Quincy, Cairo, 
Grayville (Ridgway), and from Union County. The first two records, as 
well as the last, are for the Mississippi River ; Grayville is on the Wabash 
River. Hay (1892) refers to Ridgway’s Grayville specimen, and in 
his preliminary catalogue he refers to a specimen reported by 
Garman from “a short distance 
below Mt. Carmel.” This is prob- 
ably the Grayville specimen again. 
H. Garman (1889) says for the 
Quincy region: “This species is 


said by fishermen and sportsmen 
to occur here occasionally.” To 
these published records the 
present writer adds a specimen 
(weight 96 pounds), from Mur- 
physboro on the Big Muddy River, 
now in possession of the Southern 


Hlinois State Teachers College at 
Carbondale, one specimen (weight 
33 pounds) from Chester, on the 
Mississippi, and one (weight 103 
pounds) from Metropolis from 
the Ohio River. The last two 
specimens are now in the depart- 
ment of zoology of the University 
of Illinois, in skeleton form. The 
distribution in the state is there- 


fore within the Mississippi River 


and certain of its larger southern 
tributaries. Map. 1.—Macrochelys temmincku. 


THE TURTLES OF ILLINOIS—CAHN 29 


Hasitat.—The alligator snapping turtle is a highly aquatic species. 
It shows a marked preference for soft sandy or muddy bottomed streams 
in which it may partially bury itself in the loose débris. Because of its 
great size it rarely ascends small streams, and in consequence it frequents 
normally only the larger rivers tributary to the Mississippi River, as well 
as that river itself. It is distinctly not a lake species. A certain amount 
of vegetation is greatly desired by the turtle, as this both affords protec- 
tion for it and serves as an attraction for its food. Deep holes in the 
river are its favorite resting places, and in time of danger the turtle 
retreats to the deepest, darkest hole available, where it remains for a long 
time almost immobile. It very seldom comes to land; this fact, coupled 
with its deep-water retreat, is responsible for so few being seen alive. 


Hasits.—Although this turtle has been known to science since 1840, 
its habits and life history are still to a large extent shrouded in mystery. 
Other than a mention of its presence in a few local lists and a very few 
brief references to its habits, almost nothing appears in herpetological 
literature concerning this most interesting species. 

The alligator snapper is by far the largest of the fresh-water species 
of North American turtles. Exactly how big it grows is unknown, but 
Agassiz reports having seen one alive that weighed around two hundred 
pounds; Hurter (1911) gives the measurements of one that weighed 148 
pounds (see Table 2). An animal so heavy, so awkward, so cumbersome, 
and so massively armored is essentially slow and sluggish in its move- 
ments, and the alligator snapper is not an active species: It is content 
to lie amid the soft material of the river bottom, or among the waving 
strands of vegetation, or to wander slowly over the bottom, shifting its 
great bulk slowly forward as it walks. Usually the carapace is heavily 
overgrown with algae, and this green camouflage renders the animal in- 
conspicuous in its natural haunts. Indeed, lying half buried in the dark 
muck, the strands of algae waving in the current, the turtle resembles a 
partially submerged rock. 


TABLE 2.—MEASUREMENTS OF SPECIMENS OF Macrochelys temminckit 
(Measurements in millimeters; weight in pounds) 


Carapace Plastron Head Tail 
oe Cir- Weight 
Length | Width | Length} Width | Depth | Width | cum- Total A-T 
ference 
625 533 445 vs 635 1525 148 
625 500 425 Loe ane rE 612 115 
610 462 400 | 388 186 200 627 333 1303 103 
585 448 388 362 | 186 175 602 1292 96 
567 437 nen airs 80 
453 342 303 305 175 123 385 238 822 33 


30 ILLINOIS BIOLOGICAL MONOGRAPHS 


The turtle is almost never seen on land, probably because its bulk 
and weight make for easier aquatic rather than for terrestrial locomo- 
tion. Captive specimens walk with a slow, hesitant gait when they walk 
at all, raising their great bulk clear of the ground during progression, but 
settling the plastron in contact with the ground as soon as progression 
ceases. H. Garman (1892) quotes Ridgway in regard to a specimen 
taken at Grayville, Illinois, which was “large enough to walk with a man 
standing on its back.’’ The Metropolis specimen which the writer had 
for weeks in his laboratory and which weighed 103 pounds, was capable 
of walking all around the room with a man weighing 165 pounds stand- 
ing on the shell, and seemed to do so with almost no extra effort. 

Macrochelys temmincku is extremely ferocious. Possessed of a 
vicious temper, its ire is easily aroused and, once angry, the turtle is a 
creature to beware of. The neck is rather long and the bulky head comes 
shooting out from its concealment within the shell with astonishing speed, 
and with force sufficient to throw the entire animal into the air and for- 
ward in the direction of the strike. The masseter muscles are enormous, 
often so bulky, in fact, as to make the head wider than it is long; this 
is especially true in the very large specimens. The muscles pile up on top 
of the posterior region of the skull and give the face a sharply concave 
profile. The jaws are sharp-edged and strongly hooked, and when the 
masseter gets into action, the lower jaw comes up with the snap of a 
steel trap. The 103-pound specimen was able to cut through a broom 
handle with one snap of the jaws, the cut surface appearing as if it had 
been made by a sharp axe. 

Almost the only account of the habits of this species is quoted here- 
with from Agassiz (1857); this account has reference to a specimen 
from Texas, but illustrates well the disposition of the animal: 

I kept two for several years in my fish-pond. They became very tame, but 
finding they were eating my fish I shot one, and wounded the other with a fish- 
gig; but his sagacity prevented my capturing him. I fed the perch and minnows 
with bread, which the alligator turtle devoured greedily. One day, after he had 
eaten, he remained upon the rock where I had fed him, and which was only about 
a foot beneath the surface, where it shelved over water ten feet deep. A swarm 
of minnows and perch were picking up crumbs around him, apparently unconscious 
of his presence. His head and feet were drawn sufficiently within his shell to be 
concealed. His mossy shell could not well be distinguished from the projections of 
the rock on which he was lying in ambush. Several large bass were gliding around 
him, occasionally darting at the minnows. One of these, about fourteen inches in 
length, came within striking distance of his head, which he suddenly thrust out 
and fastened upon him, fixing his aquiline bill deeply into his side and belly. He 
immediately drew the fish under him, and, holding him down firmly to the rock 
with his forefeet, ate him greedily, very much as a hawk devours its prey. I drew 
out a large line and hook and baited it with a minnow, and threw it to him, 
determined to get rid of this skilful angler. He seized it; I gave a sharp jerk, 
and fastened it in his lower jaw. Finding him too heavy to lift by the hook upon 
a rock six feet perpendicular, I led him around to the lower end of the pool, where 


THE TURTLES OF ILLINOIS—CAHN 31 


the bank was low, and the water shallow. But, after getting him within a few 
feet of the edge of the water, he anchored himself by stretching forward his 
forefeet, and resisted all my efforts to get him nearer. He seemed to be in a 
furious rage, and, after several sharp snaps at the line, he broke the hook and 
retreated into the deepest part of the pool. I never could get him to bite at any 
thing afterwards; and, finding I had a design upon his life, he became very shy. I 
afterwards discovered him in deep water, eating the bread which fell from the 
shelving rock, on which he had fed for several years, but upon which he never 
ventured afterwards when I was near. I threw a gig at him, and fastened it in his 
neck; but, by a violent effort with one of his forefeet, he tore it loose and ran 
under the rock. I frequently saw him after his escape, but always in the act of 
retreating to his hiding-place, which was entirely inaccessible. I intended sinking a 
steel trap, baited with beef, to secure this sagacious old fellow, but my removal to 
the city probably saved his life. If these two turtles made a nest or deposited 
eggs while I had charge of them, I never discovered it. They kept all their love 
for one another, and their domestic affairs a profound secret from their master. 

The mouth of the alligator snapper contains one of the most re- 
markable structures I am acquainted with, and one which deserves 
especial mention: this structure is the tongue. Dark yellow-gray in color, 
with vague, lichen-like patches and wrinkles over its surface, the tongue 
bears along its mid-dorsal line a white, fleshy object that strikingly re- 
sembles a whitish earthworm or slender grub. This object is elongated 
and tends to be round in cross-section. It is attached to the tongue over 
what is approximately the middle third of the length of this appendage, 
both ends being free. The anterior end is slightly expanded, thick, 
fleshy; the posterior end tends to taper and is more slender, terminating 
posteriorly in what looks like a small bunch of short, fleshy setae. A 
similar bristle arises from the mid-dorsal region of the attached third. 
An examination of the tongue shows that this strange object is controlled 
by a series of long, slender muscles which run to it just under the surface 
of the skin over the tongue. As to the function of this “worm” Ditmars 
(1908) has the only account of it: 

With its colours in perfect harmony, it [the turtle] lies motionless on the soft 
bottom, ready to seize, with a lightening-like dart, the suspicious fish that comes its 
way. While thus resting it is able to entice its prey by a remarkable appendage 
attached to the inside of the lower jaw, close to the region of the tongue. [As a 
matter of fact, it is on the tongue.] This is a well-developed filament of flesh, 
white and distinct from the yellowish mouthparts and resembling a large grub to 
such a degree of nicety that the popular-minded observer, seeing the object in the 
reptile’s mouth, would declare it to be the larva of some insect. More striking, 
however, is the reptile’s power to keep this appendage in motion, giving it the 
aspect of crawling about in a small, circular course. With the mud-colored shell 
lying close to the bottom, the jaws thrown open to a great extent, this organ is 
put in motion. Every other portion of the creature is as motionless as a rock. In 
this position of rigidity the shell looks like a great round stone and blotches of 
fine, waving moss intensify the deception; the big head looks like another stone, 
beneath which there is a cavern and in this cavern crawls the white grub, to all 
appearances an object dear to the hearts of finny wanderers. But woe to the luck- 
less fish that swims within reach of those yawning jaws. 


32 ILLINOIS BIOLOGICAL MONOGRAPHS 


A 33-pound specimen which the writer had in his laboratory gave 
just one very brief exhibition of the “crawling grub” act, which was 
exactly as Ditmars has described it. The control which the turtle can 
exercise over this remarkable appendage is nothing short of astonishing. 


TEXT-FIGURE 7.—The “worm” on the tongue of 
Macrochelys temmincku. 


This organ is the more remarkable when one considers that there is 
nothing parallel to it in any other American turtle. The writer would 
suggest that an interesting problem lies here in working out the embry- 
ological development and origin of this unique structure. From the point 
of view of evolution and of adaptation, it is certainly interesting to note 
that the largest of all our fresh-water turtles, a species so large and 
cumbersome as to make fish-catching by dexterity out of the question, 
we find developed a fishing lure so highly perfected and so efficient as 
to make dexterity on the part of the turtle entirely unnecessary! 


Nestinc Hapirs.—So far as I know, there is no account of the 
nesting habits in the literature, and the writer has failed entirely in ob- 
taining any information on this phase of the life history. Mr. Viosca 
writes from New Orleans that he has never seen a nest, or taken either 
the eggs or young. The smallest specimen which his field collectors have 
brought in has a carapace length of 178 mm, and this specimen he kindly 
loaned me for measurements. Agassiz figures both the egg and the newly 
hatched young, but gives no account of either. I have no idea where the 
nest is made, or how it is dug, though probably similar in many respects 
to that of Chelydra serpentina. There is no information on the number 
of eggs laid, or on the season at which laying occurs, or on the period 
required for incubation. Thanks to Dr. Loveridge of the Museum of 
Comparative Zoology at Harvard, I was able to borrow, as I have 
said, the original material from which Agassiz figured the egg (Pl. 30, 


THE TURTLES OF ILLINOIS—CAHN 33 


fig. D) and the young (PI. 1, fig. C). Search failed to yield any other 
egg or young of this species in any of the larger universities and 
museums, though perhaps some exist in institutions which I failed to 
contact. The alligator snapper is no longer nearly so common as it 
was a decade ago, and it is highly desirable that someone who has the 
opportunity work out and contribute to science the life history—yes, and 
the embryology—of this great turtle which seems to be doomed in the 
not far distant future to extinction. 


Eccs.—The eggs are perfect spheres, covered with a hard, smooth 
shell of fine texture and without a glaze. They are, naturally, the largest 
eggs laid by our North American turtles. The egg figured by Agassiz, 
the photograph of which appears in this monograph, measures 36 mm in 
diameter. 


Foop Hasits.—With such jaws as this turtle possesses, one would 
assume without any further evidence that the alligator snapper is car- 
nivorous. Such proves to be the case. The staple diet consists of fish, 
and they will apparently eat any species of any size which comes within 
catching range. I fed a sucker weighing a trifle under two pounds to the 
33-pound turtle I had in the laboratory. The turtle watched the activities 
of the fish for about five minutes, never taking its little eyes off the pro- 
spective victim. Then with a sudden projection of the head, the jaws 
closed on the side of the fish near the tail, severing completely the latter 
appendage and taking a slice of sucker as cleanly and neatly as if done 
with a sharp carving knife. This the turtle swallowed quickly, using 
the front foot to assist the morsel into the mouth. The remaining part of 
the fish was pulled apart as Agassiz has described. No doubt they would 
eat almost anything alive that came within reach, whether it be fish or 
mammal, but there is no evidence of a scavenger habit. In captivity they 
show a marked liking for bread and raw hamburger. Although other 
turtles of various pond species were kept in the same aquarium, the alli- 
gator snapper never troubled them, though they climbed and roosted 
all over it constantly. 


Economic IMportance.—So far as Illinois is concerned, the alligator 
snapper has little economic importance, due to its rarity. The meat is 
dark and strong, and has a rather offensive musky odor which might 
interfere somewhat with its palatability. Clark and Southall (1920) say: 
“Tt is especially abundant in the swamps of Louisiana, where an active 
fishery is carried on at certain seasons. It reaches an immense size. Its 
sale is confined chiefly to southern markets. As it is too large to ship in 
barrels, it is prepared for shipment by drilling holes with a breast drill 
through the edge of the upper and lower shells on each side of the neck 
and feet, running wires through and fastening it so that the head and 
legs can not be protruded.” 


34 ILLINOIS BIOLOGICAL MONOGRAPHS 


Parasites.—The leech Placobdella parasitica is common on_ this 
turtle. Of endoparasites, the nematode Zanolophorus sp. is usually 
abundant in the large intestine, over 250 having been taken from one 
specimen. Of trematodes, Lophotaspis intenora Ward and Hopkins 1931 
has been taken in the Arkansas specimen, and Distomum sp. in the form 
of very immature specimens. An undetermined Linguatulid was found in 
the large intestine. 


GENUS CHELYDRA SCHWEIGGER 


Chelydra Schweigger 1814 Saurochelys Latreille 1825 
Chelonura Flemming 1822 Cheliurus Rafinesque 1832 
Rapara Gray 1825 Emysaurus Duméril & Bibron 1835 


No supramarginal scutes between the marginals and costal scutes in 
the region of the bridge; orbit directed outward and upward; head 
covered with skin, not with symmetrically placed plates; tail with two 
rows of large scales ventrally; carapace with ridges fairly prominent in 
young specimens, becoming obsolete in large individuals; jaws moder- 
ately hooked. 

Chelydra serpentina (Linnaeus) 
(Snapping turtle; mud-turtle; hard-shelled turtle) 
Testudo serpentina Linnaeus 1758 Chelonura serpentina Flemming 1822 
Chelydra serpentina Schweigger 1812 Rapara serpentina Gray 1825 
Chelydra lacertina Schweigger 1814 Emysaura serpentina Duméril & Bibron 1835 
Emvys serpentina Merrem 1820 Chelydra emarginata Agassiz 1857 

Descrrption.—The carapace is broad and depressed, not much longer 
than it is wide. It is higher toward the anterior end than in the posterior 
region, and the anterior margin is smooth and entire while the posterior 
border is coarsely and conspicuously serrated. The vertebral scutes are 
all rectangular, the first approaching a square. The anterior and posterior 
borders of the second vertebral scute are approximately equal in length, 
but the posterior margins of the third and fourth vertebrals are shorter 
than the anterior faces. In the case of the last vertebral scute the re- 
verse is true: the anterior border is much shorter than the posterior. A 
vertebral keel is present in immature specimens, though no trace of it is 
to be found in mature individuals. The first costal is triangular; the 
remaining rectangular, the second being slightly the largest of this series. 
In young snappers and individuals approaching full growth there is a 
tendency toward a costal keel, which is very pronounced in the young 
and increasingly inconspicuous in older individuals until in fully adult 
turtles this keel is also absent. This costal keel, when present, arises 
gradually from the anterior margin of each costal scute, coming to a blunt 
point near the posterior margin. The marginals are 24 in number ex- 
clusive of the nuchal, which is well developed and costiform, extending 
long lateral arms under the anterior marginals. There are no supra- 


THE TURTLES OF ILLINOIS—CAHN 35 


marginals present as in Macrochelys temminckii. The serrations of the 
marginals are confined to the posterior three pairs for the most part, and 
there is a deep, curved notch between the caudal marginals. The plastron 
is very small and cruciform, leaving most of the soft parts of the ventral 
surface of the body exposed. The scutellation of the plastron is very 
definite and does not show the variation and eccentricities exhibited in 
the alligator snapper. Two interpretations exist for the condition found 
in the plastron: one holds that the anterior scutes are the humerals, the 
gulars being absent. This leaves an extra, elongated scute to form the 


3 

® 

¥ 
a 
i 
2 


PLate 3.—Chelydra serpentina: A, Adult, ventral view. B, Adult, dorsal view. 
C, Newly hatched young, dorsal view. D, Adult, lateral view. 


36 ILLINOIS BIOLOGICAL MONOGRAPHS 


major portion of the bridge. The second explanation is that the anterior 
plates are the gulars, in which case this extra plate becomes the dis- 
placed abdominal. The latter seems to the writer to be the correct inter- 
pretation of the situation. This elongated abdominal, then, is separated 
from the marginals by usually two inframarginal scutes, and the axil- 
laries and inguinals are very small and inconspicuous. The pectoral 
scutes are the largest of the series. The head is large, triangular, and 
flattened dorsally. It is covered with skin and does not have the bony 
plates characteristic of the alligator snapper, though the ridged surface 
of the parietal, frontal, and postfrontal bones of the skull give the top 


TEXT-FIGURE 8.—The skull of Chelydra serpentina 


of the head a roughened appearance. The snout is pointed. Both jaws 
have a median tooth, posterior to which the cutting edge of the upper jaw 
is practically straight, though both jaws are strongly hooked at the sym- 
physis. The orbits are directed outward and upward. The posterior 
portion of the head bears wart-like tubercles which increase in number 
and in prominence down the neck, and which are more numerous on the 
ventral surface. A pair of small gular barbels is located at the tip of 
the chin. Fore and hind limbs strong and powerful and covered with 
tubercles which are more prominent on the ventral surface. The an- 
terior face of the fore limbs with strong, overlapping sharp-edged scales. 
The digits are fully webbed. Fingers five in number, each bearing a 
coarse, strong claw; toes also five, the fifth, however, being rudimentary 
and without a claw. The tail is long and powerful; it is covered on the 
ventral surface by two rows of small scales, and bears a median dorsal 
row of horny tubercles, each with a bony core, and on each side a row of 
much smaller wart-like projections. 


CoLoratTion.—The carapace varies from olive brown to rich ma- 
hogany brown which in old individuals is often concealed beneath a 
thick growth of algae. In old specimens the carapace is without mark- 
ings, though in immature specimens there often shows a series of radi- 
ating black lines which focus at the apex of the costal and vertebral 
knobs. The plastron is plain, dull yellow, or buff. The soft parts are 


THE TURTLES OF ILLINOIS—CAHN 3 


N 


dark brown, darker above than below, the ventral tubercles tending to be 
light in color. The jaws are often streaked with black. 

YounGc.—Young specimens tend to be lighter and brighter in color 
than mature ones. The small snappers are very rough dorsally and show 
three conspicuous tuberculate ridges or keels on the carapace which 
grow less conspicuous as the animal matures. All keels finally disappear. 
The tail is much longer, proportionately, in young snappers: in newly 
hatched young the tail at least equals the length of the carapace, while 
in two-thirds-grown individuals it equals approximately two-thirds the 
length of the upper shell. In young individuals the color markings of the 
carapace are much more conspicuous, and the top of the head, eye-lids, 


and jaws show dark brown mottling and streaking. 


PLATE 4.—Chelydra serpentina: A, Head study of a large adult. B, Immature 
individual, four inches long, dorsal view. C, Lateral view of the same individual 


38 ILLINOIS BIOLOGICAL MONOGRAPHS 


Sex DIFFERENTIATION.—The anus of the male is nearer to the tip of 
the tail than it is in the female. 


DistRIBUTION.—The common snapping turtle, Chelydra serpentina, 
has a very wide range of distribution. From central Canada (I have 
found the species nearly to Hudson Bay) the range is known to extend 
to the Gulf of Mexico and southward almost to the equator. From the 
east the range extends from Nova Scotia and the Atlantic seaboard west- 
ward to the Rocky Mountains. It is reported as common in South Da- 
kota and Iowa. In Colorado it has been taken at least as far west as 
Boulder and vicinity. In Texas its range covers at least the eastern half 
of the state, and from here it is common eastward through Oklahoma, 
Kansas, Arkansas, and Louisiana. A closely allied species, Chelydra 
osceola Stejneger, is found in central and peninsular Florida. 

Itt1nors Recorps.—Chelydra serpentina has a state-wide distribution 
in Hlinois. Yarrow (1882) reports specimens in the National Museum 
(#9724, 12066) from Mt. Carmel; 
H. Garman (1892) from Nipper- 
sink Lake in Cook County; Green 
River at Geneseo; Quincy; 
Peoria; Havana; Normal; Cham- 


paign; Union County and Mt. 
Carmel. Hurter (1911) has 
specimens from St. Clair County, 
and Gaige (1914) from Richland 
County. Weed (1923) reports the 
snapper from Meredosia, and 
Hankinson (1917) reports it at 
Charleston. The Field Museum 
has specimens from Clinton 
(#481), Havana (1758, 2466), 
Fox Lake (1906), Olive Branch 
(2179, 2217), Meredosia (3291), 
and Highland Park (8108). The 
writer has examined specimens 
from the following _ localities: 
Havana, Peoria, Quincy, Cham- 
paign, Meredosia, Clinton, Dan- 
ville, Robinson, Middleton, Rock- 
ford, Rock Island, Pontiac, Car- 
linville, Carthage, Shelbyville, 
Louisville, Evansville, Carlisle, 


Map 2.—Chelydra serpentina. 


THE TURTLES OF ILLINOIS—CAHN 39 


Murphysboro, Carmi, Kankakee, Ottawa, Wyoming, Kewanee, Metropo- 
lis, and Horseshoe Lake in Alexander County. 

Hapitat.—The common snapper, Chelydra serpentina, is almost en- 
tirely an aquatic species. Its favorite environment is a stagnant pond 
or weed-grown lake or river. Amid the vegetation the turtles prowl for 
their food, or lie half buried in the soft mud bottom which characterizes 
waters of this type. They inhabit rivers of any size; they are common in 
the Mississippi, and I recently caught two that weighed over ten pounds 
apiece in the Embarrass River in Champaign County, where that stream 
is less than two feet wide. Though they prefer ponds and weeds, they 
are, nevertheless, sometimes found in clear streams and crystal lakes, for 
these turtles are great wanderers. While not at all abundant in the region 
of central Ontario, I have found the snapper in the rocky, inhospitable, 
cold lakes of that province. During the summer, and especially at the 
egg-laying season, the snapper is wont to wander far afield, leaving the 
water and traveling into the grassy fields or into plowed or sandy areas. 
During the seasons of excessive drought, they leave their native ponds 
as they dry up and with apparently unerring instinct travel overland to 
more congenial and habitable regions. 


Hasits.—Though very aquatic, the snappers are less able swimmers 
than other equally aquatic turtles such as the soft-shelled species of the 
genus Amyda. Their great bulk and weight make for poor swimming, 
and these turtles turn but seldom to this mode of progression. They pre- 
fer to travel by slowly and laboriously walking along on the bottom. 
They are often seen floating lazily near the surface of the lake, the shell 
entirely beneath the surface film, but the nostrils and ever-watchtful eyes | 
protruding above it. Here they paddle slowly and aimlessly about, or are 
content just to float and do nothing at all. When disturbed, or when they 
are convinced that they have been observed, the head is slowly and care- 
fully withdrawn, so slowly as to leave hardly a ripple on the surface to 
disclose their whereabouts. Once out of sight, they swim to the bottom 
and there conceal themselves. 

On land the snapper is slow and awkward in its movements. It is 
incapable of rapid locomotion because of its bulk but, having few ene- 
mies outside of man, it has little need for rapid locomotion. When walk- 
ing through a swamp or over soft ground it leaves a very characteristic 
trail, consisting of a slender somewhat undulating line made by dragging 
the heavy tail over the ground, on each side of which may be seen the 1m- 
pression of the feet. So heavy are the larger turtles that these tracks 
are often very conspicuous. When frightened or disturbed while on land, 
the turtle does not withdraw within its shell, but with jaws agape, pre- 
pares for action. It follows every motion of the intruding party, pivoting 


40 ILLINOIS BIOLOGICAL MONOGRAPHS 


awkwardly on its hind feet if necessary so as to keep its powerful jaws 
always pointed at the moving danger. It stands its ground without, ap- 
parently, the slightest idea of a passive retreat. If teased, its irascible 
temper breaks all bounds, and the turtle flings itself violently at the in- 
truder with such force as to carry it clear of the ground and considerable 
distance forward, the jaws snapping shut as the head shoots out. Once 
it fastens its jaws on an object, the snapper is extremely reluctant to let 
go again, and may be lifted clear of the ground and carried off if it makes 
contact with a stout stick. If unsuccessful after several attempts to 
reach the object of its wrath, the turtle becomes sullen and withdraws 
its head within the shell, keeping, however, the jaws fully open and 
making occasional half-hearted but dangerous lunges. The withdrawal of 
the head into the shell is accompanied by a hissing sound which is pro- 
duced by the sudden expelling of breath as the head is violently jerked 
back and the capacity for storing air is lessened. Under circumstances 
producing anger, the snapper emits a strong, musky odor which in large 
specimens is both disagreeable and penetrating. 

The snapper obtains its food either by waiting for it to come within 
range of its jaws, or by stalking it. In the first case the turtle, partially 
concealed by its growth of algae and half buried in the mud, waits pa- 
tiently for a fish or crayfish to approach; then, with a lightning strike of 
its head, it seizes its victim. When stalking its prey the turtle advances 
so slowly that its movement is scarcely discernible. The neck is extended 
and rigid; the feet are lifted and advanced with all the care and caution 
practiced by a setter advancing upon a covey of quail. When just within 
reach of its victim the jaws are slowly opened. Then the strike. 

The turtle is a voracious feeder, and from the time it emerges from 
hibernation until that condition is resumed, it feeds ravenously. Thus, 
as the summer wears on, we find the snapper “putting on” weight and 
becoming fatter and fatter until it becomes positively corpulent, great 
rolls of fat bulging over the edges of the all too small plastron. This 
stored material tides the animal over the winter months of its inactivity. 

When fall comes the snapper is among the earliest species of turtle 
to go into hibernation. During the summer this species leads a more or 
less solitary existence, each individual going its own way, and while many 
snappers may be found in a suitable pond, the species is distinctly un- 
social in its habits and not gregarious. With the approach of the cooler 
weather of October, and the ensuing drop in the temperature of the 
water, the snappers begin to congregate in places suitable for hibernation. 
At Meredosia, on the Illinois River, hibernation begins about the middle 
of October, and by the end of that month the last snapper has, as a rule, 
disappeared. A majority of the snappers go down into the mud at the 


THE TURTLES OF ILLINOIS—CAHN 41 


bottom of the pond or slough, usually to a depth of ten to twelve inches, 
where they “mud up” for the winter. Another favorite place is the 
burrow of the muskrat (Ondatra zibethica). In these burrows snappers 
congregate in great numbers. Clark and Southall (1920) report as much 
as five tons of snappers taken from such burrows at Muscatine, Iowa, in 
a single season. Twenty-six large snappers were taken from a single 
burrow, and from another runway 1420 pounds of snappers were re- 
moved. Yet another favorable site for hibernation is beneath logs par- 
tially buried in wet mud. Once they have turned in for the winter the 
snappers do not come out again until spring, usually about the middle 
of May. It is while the turtles are in hibernation that the market catches 
are made by turtle hunters. The method used is that of probing with 
a sharp stick until a turtle is located, the creature then being hauled 
out with an iron hook fixed at the end of a long stick. The gregarious 
wintering habits make wholesale catches possible, for where there is one 
turtle there usually are more. 

In captivity the snapper is sullen and always dangerous to handle. 
While they eat well they never become tame as do many of the smaller 
species. In spite of prolonged “‘hunger strikes” during which they may 
go for months without eating, the turtles live well under artificial con- 
ditions, and may be kept for years in good condition even in crowded 
quarters. 


Nestinc Hagits.—In mid-June the spirit to lay seizes the snappers 
and the female forsakes her accustomed watery environment to search 
for the right spot to deposit her eggs. I have trailed snappers for more 
than half a mile from water during the egg-laying season. In regard to 
the site chosen for the nest, I cannot refrain from inserting the admir- 
able account by Professor Jenks, which Babcock (1919) quotes: 


Leaving my horse unhitched, as if he, too, understood, I slipped eagerly into 
my covert for a look at the pond. As I did so, a large pickerel ploughed a 
furrow out through the spatterdocks, and in his wake rose the head of an 
enormous turtle. Swinging slowly around, the creature headed straight for the 
shore, and without a pause scrambled out on to the sand. She was about the size 
of a big scoop-shovel; but that was not what excited me, so much as her manner, 
and the gait at which she moved; for there was method in it and fixed purpose. On 
she came, shuffling over the sand toward the higher open fields, with a hurried, 
determined seesaw that was taking her somewhere in particular, and that was 
bound to get her there on time. I held my breath. Had she been a dinosaurian 
making Mesozoic footprints, I could not have been more fearful” For footprints 
on the Mesozoic mud, or on the sands of time, were as nothing to me when 
compared with fresh turtle eggs on the sands of this pond. But over the strip of 
sand, without a stop, she paddled, and up a narrow cow-path into the high grass 
along a fence. Then up the narrow cow-path on all fours, just like another turtle, 
I paddled, and into the high, wet grass along the fence. I kept well within sound 


42 ILLINOIS BIOLOGICAL MONOGRAPHS 


of her, for she moved recklessly, leaving a trail of flattened grass a foot and a 
half wide. I wanted to stand up—and I don’t believe I could have turned her 
back with a rail—but I was afraid if she saw me that she might return indefinitely 
to the pond; so on I went, flat on the ground, squeezing through the lower rails 
of the fence, as if the field beyond were a melon-patch. It was nothing of the 
kind, only a wild, uncomfortable pasture, full of dewberry vines, and very dis- 
couraging. They were excessively wet vines and briary. I pulled my coat-sleeves 
as far over by fists as I could get them, and with the tin pail of sand swinging 
from between my teeth to avoid noise, I stumped fiercely, but silently on after the 
turtle. She was laying her course, I thought, straight down the length of this 
dreadful pasture, when, not far from the fence, she suddenly hove to, warped 
herself short about, and came_ back, 

barely clearing me, at a clip that was 

thrilling. I warped about, too, and in msl>N Lg! 


her wake bore down across the corner Ss, 

of the pasture, across the powdery pub- Nat 

lic road, and on to a fence along a field NS. 

of young corn. I was somewhat wet by SNe : ze’ 
this time, but not so wet as I had been Ete bee 
before wallowing through the deep, dry Nh, He ‘ 
dust of the road. Hurrying up behind eee 

a large tree by the fence, I peered down a 
the corn-rows and saw the turtle stop, SS 
and begin to paw about in the loose soft \\ 20° 
soil. She was going to lay. I held on to aw 
the tree and watched, as she tried this Paid 
place, and that place, and the other ie 
place—the eternally feminine. But the i! Wate 
place, evidently, was hard to find. What ater. 


could a female turtle do with a whole TextT-FIGURE 9—Showing the wan- 


field of possible nests to choose from? 
Then at last she found it, and whirling 
about, she backed quickly at it, and, tail 


dering of a female Chelydra serpen- 
tina in search of a nesting site; black 
dots indicate holes dug. 


first, began to bury herself before my 
staring eyes. 

If the nest site be a vertical bank of soft material, the turtle backs 
into it, causing the loose material to fall upon her carapace until she may 
be completely hidden from view. When she comes out, climbing uphill 
to do so, the material on her back slides down into the hole and buries 
the eggs. If digging into a flat field, the hole is scratched out with the 
claws, the turtle backing into it as the digging progresses. The nest itself 
is a chamber considerably wider than the tunnel leading down to it from 
the surface, and is an expansion to one side of the axis of the tunnel. 
It often les a foot below the surface, the angle of the tunnel being 
between 45° and 60° with the horizontal. In this subterranean chamber 
the eggs are laid, often in two or three layers, with no dirt between the 
strata. Occasionally odd nesting sites are chosen, such as the cinder 
area between the tracks of a railroad right of way, where I once saw 
one digging. 


THE TURTLES OF ILLINOIS—CAHN 43 


Eccs.—The snapping turtle usually lays her eggs early in the day and 
is seldom found laying after ten or eleven o'clock in the morning. These 
eggs are perfectly spherical and are covered with a tough, white shell. 
So strong is this shell membrane that the egg will bounce several times 
if dropped on a hard surface. In a fresh egg one pole is white, the other 
pinkish, and the egg contains a very large air chamber occupying nearly 
half the space within the shell. There is a great discrepancy in litera- 
ture as to the number of eggs laid by a single female in her nest. Thus 
Surface (1908) says that “from twenty to one hundred may be laid in 
one nest, according to the size of the female,” while Hay (1892) gives 
the number as “from 30 to 70.” The writer doubts very much that these 
high numbers represent the egg complements of one female, since, after 
examining a great many female snappers, there is every evidence that 
the average number is far below this. From 20 to 30 eggs constitute a 
normal clutch, and when a much larger number is reported, the con- 
clusion must be drawn that more than one turtle is responsible. Since the 
turtle has, at the time of laying her eggs, not only the eggs to be laid 
that season in her body but also the growing eggs for the succeeding 
season, care must be taken in counting the eggs in the body cavity not to 
confuse clutches which will mature during different years. In size the 
eggs measure about 33 mm on an average. The incubation period is not 
known. The young snappers extricate themselves from the egg by means 
of a tiny “egg tooth” on the tip of the snout, with which they pick away 
the shell. 

Foop Hagits.—The common snapper is largely a carnivorous species 
A list of the animals upon which it normally preys would run through 
many of the classes of animals, both vertebrate and invertebrate, which 
are available for it to feed upon. Among the vertebrates, fish, frogs, 
tadpoles, salamanders, snakes, birds, and mammals are commonly found 
in the digestive system, while among the invertebrates, snails, insects, 
insect larvae, and crayfish are predominant. Fish and crayfish probably 
make up the bulk of the food, because both of these animals are common 
in the habitat selected by the snapper. Aside from these items, the turtles 
are scavengers and will clean up any carcasses or meat thrown into the 
water in which they live. Thus I have found bones of animals such as 
dogs, cats, and rabbits in the stomach, as well as pieces of bones of much 
larger animals showing the saw marks of the butcher. The marvel is 
how these great masses are eventually passed from the digestive system 
without tearing it to shreds. All food taken is swallowed under water 
and apparently the turtle is unable to swallow unless beneath the surface. 
Young ducks are often captured, the turtle grabbing them by their 
submerged legs and dragging them under water, there to drown and be 


44 ILLINOIS BIOLOGICAL MONOGRAPHS 


pulled to pieces by the hawk-like beak. In spite of their preéminently 
carnivorous habits, occasional individuals are found whose stomach is 
full of grass, leaves, and other vegetable matter. Sometimes this repre- 
sents aquatic vegetation, but more often terrestrial plants. In other 
words, when the turtle is out of water it cannot obtain its usual animal 
food, yet it is adaptive enough to subsist on a vegetable diet. The young 
feed on insect larvae which they find buried in the mud. 


Economic IMportaANce.—That the snapping turtle destroys a great 
many fish is a fact. The list of species identified includes such forms as 
the crappies, the sunfishes, perch, bass, suckers, carp, and a large variety 
of minnows. In spite of this, in many localities the species of fish eaten 
are of little or no economic importance to man. Along the Illinois River 
these turtles, caught in hoop nets, often destroy a considerable number 
of valuable fish before the fishermen arrive to take up the nets; also 
they are powerful enough in some cases to tear their way out of the net, 
leaving a fine exit for the captive fish. Their destruction of young ducks, 
both of domestic and wild species, is often serious. Since wild ducks and 


TABLE 3.—MEASUREMENTS OF THE SNAPPING TURTLE, Chelydra serpentina 
(Measurements in millimeters; weight in grams) 


Carapace Plastron Tail 
SuiseisGe Head Weight | Sex 
Length | Width | Length} Width | Depth Total A-T 
232 187 160 156 04 50 aly 156 2450 2 
Saif 271 231 230 122, fl 270 190 5906 
59 50 40 36 28 14 55 45 58 
320 272 224 220 110 62 245 195 5783 
202 170 144 207; 85 45 170 139 1606 
272 231 197 100 61 200 172 25211 
300 256 219 AG 275 


birds of similar habits tend to breed in the proximity of weedy lakes 
and take their broods of young into such ponds immediately after hatch- 
ing, and since such ponds form the natural habitat of the snapper, this 
depredation is greater than it would at first appear. In Ontario I have 
seen Snappers catch young loons. 

Set against these items which must be checked as detrimental from 
the point of view of man, we have the scavenger habits of the turtle 
and its economic importance as a food animal. The snapper will eat any 
dead animal matter it comes across—including fish left on a stringer in 
the lake by careless fishermen. Since their capacity seems almost un- 
limited, they play an important part in the “clean-up” of waters polluted 
by waste material of this nature. As food for man the snapper affords 


THE TURTLES OF ILLINOIS—CAHN 45 


an easily obtained and usually available supply of wholesome, nutritious 
meat. The meat is likely to be rather “strong” and, so far as I per- 
sonally am concerned, one must acquire a taste for turtle meat. A large 
individual yields a surprising quantity of flesh: one can figure on obtain- 
ing an amount of eatable meat equal to about one-half of the total 
weight of the turtle. The market value is about twenty-five cents 
a pound, dressed, and the turtle, therefore, becomes one of the cheapest 
of the available meats. In spite of this fact, the market for snappers has 
steadily decreased during the last decade. 


PaRASITES.—The snapper is almost always heavily infested with the 
leech Placobdella parasitica, and 1 have removed 44 specimens from a 
twelve-pound turtle taken at Meredosia. The leeches congregate espe- 
cially in the angles under the fore and hind limbs, about the anus, and 
around the eye sockets. Nematodes of the species Spironoura chelydrae 
are often extremely abundant in the intestine. The trematode Allossos- 
toma parvum Stunkard has been taken from snappers at Urbana, as has 
the trematode Camallanus trispinosus (Leidy). 

MisceLtaNy.—There is on hand an unusual carapace of Chelydra 
serpentina, taken from the Rock River at Rockford in 1927, now the 
property of the State Natural History Survey. This carapace presents 
a most weird appearance. In the first place, it is highly domed like a 
derby hat; in the second place, it is wider than it is long. It is perfectly 
formed as to osseous elements and normal as to scutes, excepting only 
that the costal scutes are greatly elongated to compensate for the doming. 
The following measurements of the carapace are of interest: 


Freak Normal 
ILGiaveadn, Serraino eo oa 221 mm 313 mm 
Waid thieenie ssceveten ein avete 257 mm 256 mm 
MEV@1 Oliteye cae ecte sere cue © 128 mm 84 mm 


Regarding this specimen, Dr. David H. Thompson of the Natural History 
Survey, who saw the turtle alive, writes: “This turtle was caught by 
some boys in the fishway of the Oregon dam on the Rock River in June, 
1927. It was kept alive for several weeks at Rockford, where I saw it 
and had the opportunity of watching its unusual behavior. The head 
and legs were of a size in keeping with a very much larger individual. 
When it walked on land it did not drag its plastron on the ground as is 
usual, but walked upon its tip-toes, with the body carried two or three 
inches clear of the ground. This habit of walking, together with its 
very long legs and neck, gave it a very grotesque appearance.” 


46 ILLINOIS BIOLOGICAL MONOGRAPHS 


FAMILY KINOSTERNIDAE 


Kinosternon Spix 1824 Cinosternidae Agassiz 1857; Cope 1882 
Emydidae (part) Gray 1825; 1844; 1855 Chersemyda (part) Strauch 1862 
Steganopodes (part) Wagler 1830 Chelydradae (part) Gray 1870 


Emydae (part) Gray 1831 
Elodites Cryptoderes (part) Duméril & Bibron 1835 


EXTERNAL D1aGNosts.—Carapace elongate, oval, either highly con- 
vex or relatively flat; usually smooth, but keeled in one species; mar- 
ginals 23 in number, not flaring. Nuchal scute small dorsally, but larger 
ventrally, underlying the adjacent marginals. Plastron moderately large, 
rounded anteriorly and either truncate or shallowly emarginate poster- 
iorly. Dermal skeleton covered with epidermal scutes. Plastron with 10 
or 11 scutes, the anterior pair coalescing into one in some species; anter- 
ior lobe movable upon a fixed central portion. Pectoral scutes widely 
separated from the marginals. Axillaries and inguinals, together with 
the wings of the abdominals, forming the bridge. Neck completely 
retractile within the shell. Head large, pointed, with a large rhomboidal 
plate dorsally and with a projecting snout. Lower jaw terminating in a 
sharp point. Eyes located well toward the anterior end of the head. 
Digits moderately well developed; webbed. Five fingers and four toes 
bearing claws. Tail terminating in a nail. 

OstEoLocicaL Dr1aGNosis.—Plastron composed of eight bones, the 
entoplastron being absent. Nuchal plate produced into costiform proces- 
ses underlying the marginals. Temporal region not roofed over; no 
parieto-squamosal arch present. Pubic-ischial symphyses in contact, 
separating two foramina. Phalanges with condyles. Caudal vertebrae 
procoelous. 


GENUS STERNOTHERUS (GRAY) 


Sternotherus Gray 1825 Kinosternum (part) LeConte 1854 
Kinosternon (part) Spix 1824 Armochelys Gray 1855 
Sternothaerus Bell 1825 Cinosternum Agassiz 1857 
Cinosternon (part) Wagler 1830 Ozotheca Agassiz 1857 
Staurotypus (part) Duméril & Bibron 1835 Goniochelys Agassiz 1857 


Plastron narrow, approaching cruciform; posterior lobe not more 
than one-half the width of the aperture and longer than the anterior 
lobe; lobes but slightly movable and incapable of closing the aperture. 
Wings of abdominal scutes narrow, not grooved posteriorly; much 
cartilaginous material between certain plastral elements centering around 
the abdominals. Carapace highly arched or domed, unkeeled; first ver- 
tebral scute in the form of a long, narrow triangle. 


THE TURTLES OF ILLINOIS—CAHN 47 


Sternotherus odoratus (Latreille) 
(Musk turtle; stink-pot) 
Testudo pensylvanica, B., Schoepff 1792 Kinosternum guttatum LeConte 1854 


Testudo odorata Latreille 1802 Aromochelys odorata Gray 1855 
Testudo glutinata Daudin 1802 Ozotheca odorata Agassiz 1857 
Emys odorata Schweigger 1814 Ozotheca tristycha Agassiz 1857 
Terrapene boscu Merrem 1820 Goniochelys triquetra Agassiz 1857 
Terrapene odorata Merrem 1820 Aromochelys guttata Strauch 1862 
Cistuda odorata Say 1825 Aromochelys tristycha Strauch 1862 
Sternothaerus odoratus Bell 1825 Cinosternum odoratum Boulenger 1889 
Sternothaerus, bosctt Bell 1825 Alromochelys carinata (part) Garman 
Kinosternum odoratum Bonaparte 1830 1892 
Kinosternon odoratum Gray 1831 Aromochelys odoratus Davis & Rice 
Staurotypos odoratus Duméril & Bibron 1883 

1835 


DescripTion.—Carapace long and somewhat narrow, widest poster- 
iorly through the seventh marginal scute, the curvature being almost 
_alike at the anterior and posterior ends. The shell is highly arched, 
rounded, and in old individuals smooth, but there is occasionally a faint 
trace of the vertebral keel which is prominent in young individuals. The 
nuchal scute is very small, hardly larger in the adult than in a newly 
hatched young. The first vertebral scute is greatly elongate, triangular, 
the apex pointing backward; the second, third, and fourth vertebrals are 
more or less hexagonal or shield-shaped, the fourth being the smallest 
of the series. The anterior margin of the last vertebral scute is approxi- 
mately half as wide as its posterior margin. The costals are enormously 
large, covering the greater portion of the carapace, the posterior lateral 
angles of the first three curving backward. The marginals are elongate 
and narrow, with the exception of the last pair and the caudals, which 
two pairs are fully twice the width of the other marginals. The plastron 
is small, not nearly covering the soft parts, and is rounded anteriorly and 
truncate posteriorly. It differs from the plastron of other Illinois turtles 
in that the adjacent (paired) scutes do not touch each other, being 
separated by a cartilaginous mass of varying diameter. The single gular 
is very small; the humerals are small, the pectorals being about twice 
their size. The abdominals are by far the largest of the ventral scutes. 
The narrow bridge is formed by a small wing of the abdominal and 
the axillary and inguinal scutes which intrude themselves between the 
abdominals and the marginal plates so that these do not make contact. 
There is a movable transverse hinge between the pectoral and abdominal 
scutes, and a less movable hinge posterior to the abdominals. Head large, 
the snout projecting; the jaws are strong, the lower being hooked. Two, 
three, or four gular tentacles at the tip of the chin, and another pair, 
more widely separated, farther back on the neck, which is very long. 


48 ILLINOIS BIOLOGICAL MONOGRAPHS 


The feet are large, the toes webbed; digits 5-4, the claws small and 
short. The anterior border of the front legs bears three elongate trans- 
verse scales; the posterior limbs exhibit a small series of similar scales 
on the heels. The skin is everywhere covered with small fleshy papillae. 


CoLoraTION.—Carapace brownish olive or dark “‘horn” color above, 
darkest toward the mid-dorsal line and shading into yellowish on the 
marginals. Usually uniform in color, but sometimes exhibiting dark 
transverse lines especially on the costals. Often the carapace is so 
overgrown with algae as to completely obscure the markings. Plastron 
yellowish, sometimes with indications of dark brown blotches or lines 


TEXxT-FIGURE 10.—-Plastron of male and female Sterno- 
therus odoratus to show sex variation in the amount of 
cartilage (stippled). d—abdominal; An—anal; F—femoral; 
G—gular; H—humeral; P—pectoral. 


along the sutures, the fleshy or cartilaginous parts between the scutes 
with a decidedly pink tint. Head and neck dark olive. A short yellow 
stripe extends along the edge of the snout to the anterior margin of the 
eye and continues vaguely posterior to it, to terminate in an irregular yel- 
low spot above and behind the ear. A second stripe begins just ventral 
to the nostril and extends backward along the side of the neck, passing 
below the tympanum. The extent of the first mentioned stripe shows 
great variation, and the second stripe may occasionally be absent. The 
lower jaw is mottled with yellow. The papillae are for the most part 
yellow or orange against the dark olive of the skin. 

Younc.—In young specimens just hatched (carapace length 23 mm), 
the carapace is rough and exhibits three distinct and conspicuous keels: 
one mid-dorsal and extending down the vertebral scutes, and a pair of 
lateral keels along the upper third of the costal scutes. In arrangement 
these are not unlike those of the young snapping turtle Chelydra serpen- 


THE TURTLES OF ILLINOIS—CAHN 49 


tina; indeed, young Sternotherus odoratus are more often than not con- 
fused with this species. The surface of the carapace is roughened by 
tiny irregularities which disappear with age, giving it a sandpaper-like 
appearance. Carapace highly arched and nearly black in color. Plastron 
grayish, mottled with pale yellow; a pale yellow spot on the mid-ventral 


Pirate 5.—Sternotherus odoratus: A, Adult female, ventral view. B, Dorsal 
view of the same individual. C, Young specimen, three and a quarter inches long, 
dorsal view. D, Adult, lateral view. 


50 ILLINOIS BIOLOGICAL MONOGRAPHS 


surface of each marginal scute. In young 42 mm long the mid-dorsal 
vertebral keel is still very prominent and highly notched, but the costal 
keels are reduced to a terminal nob at the posterior margin of each scute. 
Both carapace and plastron are now a lighter brown and the plastron 
shows a greater amount of yellow mottling. The stripes on the head are 
usually very conspicuous at this stage of growth. 


Sex DIFFERENTIATION.—The tail is much longer and stouter in the 
male than in the female, and usually bears a blunt terminal nail. The 
dorsal surface of the tail in the male is smooth, while there is a mid- 
dorsal row of tubercles down the tail of the female. The plastral scutes 
of the males are smaller than those of the females of the same size, the 
areas between the scutes in the males being in consequence larger (see 
Text-fig. 10). The male exhibits two oval patches of scales on the inner 
surface of the hind limbs, one above and one below the knee, these areas 
being absent in the female. In cross-section, the plastron of the male is 
concave, that of the female flat or slightly convex. 


GEOGRAPHICAL DrIstRIBUTION.—Sternotherus odoratus is a species 
which has a very wide distribution over the United States. Its range 
extends over the entire eastern portion of the country to Maine and 
Massachusetts ; westward it extends to western Missouri and Texas. The 
northern limit is southern Canada, from which it extends southward to 
and including Florida. Over the greater part of this vast range the 
species is common, becoming distinctly less abundant in Missouri and 
northeastern Texas. 


IttrNo1s Recorps.—This species is reported by H. Garman (1892) 
from Deep Lake in Lake County; Chicago; Peoria; Little Fox River at 
Phillipstown; and from Running Lake in Union County. Hurter (1911) 
records it from Madison and St. Clair counties on the Mississippi River ; 
Weed (1923) from Meredosia on the Illinois River; Hay (1893) from 
Mt. Carmel on the Wabash. Blanchard (1924) reports it from Carrier 
Mills in Saline County, and Yarrow (1882) records a specimen (#14) 
in the U. S. National Museum from Chicago. In the Field Museum in 
Chicago are specimens from Momence (#323), Havana (#1754), and 
Homewood (#4092). The writer has examined many dozens of speci- 
mens from the following localities: Meredosia, Havana, Peoria, Rock- 
ford, Rock Island, Prophetstown, Aurora, Pontiac, Petersburg, Vandalia, 
Metropolis, Cairo, Mt. Carmel, Chester, Lawrenceville, and Quincy. In 
so far as the distribution within the state is concerned, the species is 
decidedly more abundant in the southern half than in the northern, and 
more common toward the east than toward the west. In terms of the 
number of individuals per given area it is more abundant in the Illinois 
River than in any other large stream within the state. 


THE TURTLES OF ILLINOIS—CAHN 51 


Hasitat.—This little species 
is highly aquatic in its habits, 
showing a marked preference for 
the smaller lakes and streams. 
The ideal habitat is a small, slow- 
moving, muddy-bottomed stream 
having an abundance of aquatic 
vegetation, or a  semi-stagnant 
slough. They tend to avoid clear- 
water lakes, as well as all gravel 
or rock-bottomed waters. Small 
vegetation-choked lakes are an 
ideal environment, and in such 
localities they pick the deeper 
portions, seldom coming to land. 
So far as streams are concerned, 
the species tends to avoid the 
larger rivers, as is well illustrated 
by the situation at Meredosia on 
the Illinois River. While Sterno- 
therus odoratus is found in the 
main channel of the river to some 
extent, the numbers in such a 
locality are as nothing when com- 
pared to the abundance of the 
species in Meredosia Bay. 


Map 3.—Sternotherus odoratus. 


Hasits.—Probably the most aquatic of our local turtles, not except- 
ing the soft-shells (Amyda) or the snapper (Chelydra). So aquatic is 
the musk turtle that it seldom comes to dry land, being content to wander 
about amid the bottom mud and vegetation of the lakes and streams. This 
tendency accounts for the overlooking of the species by observers in many 
localities where it is really common, for, unless one goes out looking for 
it, one is likely never to suspect its presence. For eleven summers the 
writer collected in the clear-water lakes of southeastern Wisconsin with- 
out ever seeing a musk turtle. Early one June morning he found one 
crossing the road coming from a swamp area. Later in the day he 
seined a pond in the middle of the swamp and captured 52 specimens in 
half an hour. The puddle was alive with them, their pointed snouts 
poking through the vegetation-covered surface, yet all but invisible amid 
the tangle of reeds and rushes. On a half-submerged log eight specimens 
were basking in the sun, only to disappear into the water at the first hint 
of danger. Where the species is found it is likely to be abundant, but 


BY ILLINOIS BIOLOGICAL MONOGRAPHS 


since it shows such a definite environment preference, it is likely to be 
of very local distribution. 

The musk turtle is well adapted to its aquatic habitat. The feet 
are large, the toes well webbed. It can swim rapidly and strongly when 
necessary, but it prefers to wander aimlessly about on the bottom, poking 
about among the plant stems and bottom débris in search of food. It 
walks slowly along on the bottom, moving its head from side to side to 
peer under a dead leaf or to push half its body into the soft mud under 
a piece of rotten wood. The very long neck is highly mobile and the 
strong jaws snap voraciously and retain whatever food they find. When 
not wandering, the musk turtle may remain for hours at a time entirely 
motionless under a log, the head partially retracted. At such times the 
“moss” covered shell blends admirably with the bottom vegetation and 
affords the turtle what little protection it needs in its naturally somewhat 
opaque and dark surroundings. 

Its highly aquatic adaptation has been shown by Ditmars (1908) who 
kept the musk turtle in a deep aquarium for several weeks. Here the 
turtles swam and crawled about in entire comfort, paddling to the sur- 
face occasionally for air, yet having no out-of-water footing. Under 
similar conditions almost every other species (except probably Chelydra 
serpentina) will die of exhaustion in a few days. The writer carried this 
experiment further, and kept Sternotherus odoratus under similar condi- 
tions for eighteen weeks without harm to the turtles. 

The musk turtle is very timid by nature. The least disturbance sends 
it scurrying off its basking log, to which it will not return for hours 
after the danger is past, and then only after a prolonged, careful scrutiny 
of the situation from its nearly submerged position. When disturbed 
while on land, the head is retracted quickly, the legs drawn in, and the 
tail curled tightly under the shell. Thus it remains motionless for a long 
time. Eventually the head begins slowly to protrude, so slowly that its 
movement is barely perceptible. Then, after watching carefully for the 
least inkling of danger, the legs and tail are brought forth and the turtle 
resumes its journey. The manner of withdrawing within the shell is 
peculiar and is described by Agassiz (1857) as follows: 

The forelegs are carried round before the body; the elbow, somewhat raised, 
is carried directly back by the side of the head and neck into the scapular arch, 
the skin at the same time rolling off toward the feet and shoulders and leaving its 
muscles as naked as those of the neck and scapular arch about it; the forearm is 
turned back, but not quite on to the humerus; the hand is either laid in against 
the head and neck, or turned back on to the humerus. .. . The hind legs are with- 
drawn nearly horizontally, the knees like the elbows, though in a less degree, 
stripped of the skin; the foreleg is turned back upon the femur, and the foot 
again turned forward upon the foreleg. The tail is turned to one side. The head 


is drawn back to within the scapular arch, the skin rolling off from the neck, 
but not folding together before the head, as in the Emydoidae. 


THE TURTLES OF ILLINOIS—CAHN 53 


If annoyed or molested to a point where its slow anger is aroused, 
the turtle snaps viciously at any object within reach. The jaws are 
opened wide while the head is still completely withdrawn; then the head 
and long neck are slowly projected and moved toward the offending 
object. A sudden snap over a short distance, and the jaws close upon 
whatever disturbing element is within their reach. If they close upon the 
object of their wrath, the turtle attempts to retract the head again under 
the shelter of the carapace, still holding to the captured object. 

When handled, or when its anger is awakened, the turtle emits a 
strong fetid or musky odor, which is responsible for the common name 
of “musk” turtle. This is due to a secretion emitted by a pair of well- 
developed glands which underlie the anterior lateral angles of the cara- 
pace. The material secreted is highly volatile, and the odor characteristic 
of the kinosternid group permeates the atmosphere for a distance of some 
feet. Sternotherus odoratus probably has these glands developed to a 
greater extent than any other member of the family; certainly the odor 
emitted is stronger than in any other species. 

The males bear “stridulating organs” on the hind leg, as has been 
mentioned. By rubbing these patches of horny tubercles together, they 
are reported to make “stridulating sounds,” but the present writer has 
not observed this performance. Whether this is associated with the 
mating phenomena is not known. 


NestinG Hasirs.—There are but a few descriptions available of the 
nesting habits of this turtle, and these vary considerably. The summer 
work of Mr. Combs at Meredosia yielded no data on this subject, but 
the writer has twice seen the nest-digging in southeastern Wisconsin. In 
one instance the nest was in the sand about 150 feet from the pond in 
which the turtle lived. At 6:20 on the evening of June 22, the female 
came slowly out of the water and paused for about ten minutes at the 
water’s edge while she looked about with her head raised to the fullest 
extent. Satisfied that all was well she headed off through the tall reeds 
straight for the patch of sand; there was no uncertainty in movements. 
Arriving here she paused again for a few minutes, her head again erect. 
Then she walked deliberately out to nearly the middle of the open area 
and began to dig. The process was slow and leisurely, the dirt being 
scraped away with alternating strokes of the hind feet, and piled up into 
two small heaps on each side of the hole. When the depth of the hole 
was about equal to the length of the carapace, she deposited her eggs 
therein, after which she filled in the hole again with her hind feet and 
headed straight back to the water. The time required for the digging, 
laying, and covering was forty-seven minutes, during which time she paid 
no attention to anything around her. When I dug the nest out I found 
it to be semicircular in shape, the roof arched to conform to the curva- 


54 ILLINOIS BIOLOGICAL MONOGRAPHS 


ture of the carapace. The hole descended at an angle of 50° to a depth 
of four and a half inches, and contained three eggs. The second case 
was similar in all particulars save only that this time the nest was dug 
in the grass of a lawn a hundred feet from the water and fifty feet 
above it on a hilltop. Here the ground was much harder; the nest was 
but two and three quarters inches deep, yet required nearly an hour for 
excavation. A distinct variation in nesting habits is reported by Eigen- 
mann (1896) for the Turkey Lake country of Indiana: “The eggs are 
laid in the rotten wood in the tops of stumps standing in the margin of 
the lake. The turtles were frequently found in the tops of these stumps, 
and some of their eggs wedged as far into the rotten wood as the finger 
could bore. Rotten logs removed some distance from the water are also 
favorable places for egg-laying, and in a mucky place of small area at 
the edge of the lake 362 eggs were taken at one time. While passing 
along a wheat field some turtles were seen coming from it, and on 
inspection it was found that they had deposited their eggs in the ground 
in depressions made by a cow while walking over the ground when it 
was soft. Still other eggs were found in bundles of rushes drifted 
together.” That this stump-utilization habit is unusual is indicated by 
Eigenmann’s further statement: “The present large number [of stumps] 
is due to the rising of the lake after the building of the dam and the 
subsequent cutting down of the trees whose boles had become sub- 
merged. The habit of laying eggs in stumps cannot be much more than 
fifty years’ duration.’ Quite frequently the writer has found stray eggs 
lying about in swamps, indicating that the female had passed an egg 
without any attempt at nest-building at all. Such eggs never hatch. 

From circumstantial evidence at hand it would seem that the musk 
turtle lays either early in the evening, at night, or very early in the 
morning. Agassiz reports seeing it laying at half-past eight in the eve- 
ning. The normal laying season in Illinois seems to be late in June. In 
southeastern Wisconsin I once found the nest of Sternotherus odoratus 
containing two eggs with very young living embryos within, on Sep- 
tember 22. Whether this is a freak, or whether there may perhaps be a 
second laying season under particularly favorable climatic conditions, 
is not known. Neither is it known whether these young turtles would 
have hatched that fall or have ‘‘wintered’”’ within the egg. Agassiz 
reports Cinosternum pensylvanicum (= K. subrubrum) laying one egg 
on October 7 which was, however, apparently unfertilized. 

Eccs.—The normal egg complement is three, though occasionally four 
or five eggs are encountered. Babcock (1919) reports as many as seven 
in a clutch. The eggs are of an elongated elliptical shape, the ends 
equally rounded, and are covered with a hard, smooth shell of very fine 


THE TURTLES OF ILLINOIS—CAHN 55 


texture. This shell is exceedingly brittle. The average of 112 eggs meas- 
ured by the writer shows their size to be 27.6 mm in length by 14.8 mm 
in width. Of the period of incubation nothing is known. The chief 
enemies of the eggs of this turtle are the skunk and the raccoon. Both 
of these animals have a decided fancy for turtle eggs, and the writer has 
found dozens of nests which have been dug out by them, the discarded 
eggshells lying about the excavation. 

Foop Hasitrs.—Sternotherus odoratus is primarily a carnivorous 
species, feeding principally upon aquatic insects, tadpoles, worms, mol- 
lusks, crayfish, and occasionally upon small fish. Insects such as grass- 
hoppers and beetles are often found in the stomach contents, these 
probably being individuals that fell into the water and were snatched 
from the surface film by the ever-watchful turtle. Snails and clams, 
always species of small size, are often eaten. The species of fish which 
have been taken by the writer from the stomachs examined have always 
been “minnows”: Umbra limi, Notropis whip plii spilopterus, Poecilichthys 
sp., Notemigonus crysoleucas auratus. Fishermen who practice their art 
in the shallow, weedy lakes, often catch these turtles on their hooks, 
particularly if still-fishing with live worms or grubs. 

Economic Importance.—This species, the smallest of our native 
Illinois forms, has practically no economic status one way or the other. 
Their flesh is never eaten because of the musky flavor, and they have 
but little tendency toward the habits of a scavenger. The fish they eat 
are of no consequence to anyone. They have been reported to eat fish 
eggs, but this certainly is a minor item in their diet and of no importance. 


TABLE 4.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Sternotherus odoratus, 
(Measurements in millimeters; weight in grams) 


Speci Carapace Plastron 
cpa Head | Tail |Weight| Sex 
’  |Length| Width | Length} Width | Depth 


i eeeeeere. oe 123 83 94 56 51 28 41 ec ros 
Di nae 119 80 94 56 50 26 30 253 g 
ee ahcrncerets 124 82 87 |- 52 42 25 40 233 fof 
Aaa: ae 109 77 79 53 39 24 36 176 ce 
Somme 101 70 75 49 36 23 35 134 ef 
One ceeee 93 69 74 BS) 36 20 30 124 ro 
ase 90 65 72 50 35 ie) 26 119 of 
Be ces een 89 66 69 50 34 17 29 109 2] 
rare 112 75 86 56 41 25 28 185 is) 
LO sis ens 128 81 90 58 44 27 48 238 ist 
Velie saved’ 110 76 79 55 40 26 43 188 g 
1D Se ore 104 73 80 54 41 22, 170 ro 
LS istencon eens 111 81 86 57 42 23 25 201 (ae 
Q 


56 ILLINOIS BIOLOGICAL MONOGRAPHS 


ParasiTEs.—The musk turtle is almost always the host to a large 
number of leeches. The commonest species found on them is Placobdella 
parasitica, which attaches itself in numbers to the soft parts, but which 
apparently does the turtle no harm. On one occasion, however, I found 
a turtle in which a leech of this species had worked itself into the eye 
socket and had caused blindness in the associated eye. Internally nema- 
tode parasites are usually very abundant from the posterior end of the 
stomach through the small intestine. 


GENus KINOSTERNON SPIX 


Terrapene (part) Merrem 1820 Kinosternum LeConte 1854 
Kinosternon Spix 1824; Bell 1825 Goniochelys Agassiz 1857 
Cinosternon Wagler 1830 Cinosternum Agassiz 1857 
Uronyx Rafinesque 1832 Thyrosternum Agassiz 1857 
Monoclida Rafinesque 1832 Platythyra Agassiz 1857 
Staurotypus (part) Duméril & Bibron Swanka Gray 1870 

1835 


Plastron moderately wide, the posterior lobe about two-thirds the 
width of the aperture and approximately equal in length to the anterior 
lobe; emarginate posteriorly and with rounded lateral angles; each lobe 
movable on a transverse hinge and capable of partially closing the aper- 
ture. Wings of the abdominal scutes wide and bearing a posterior groove. 
Carapace somewhat depressed rather than domed; first vertebral scute 
widely triangulate, the anterior base being two-thirds to three-fourths 
the height of the scute. 


Kinosternon flavescens (Agassiz) 


Platythyra flavescens Agassiz 1857 Kinosternum flavescens Cope 1892 

Cinosternum flavescens Cope 1875 Kinosternon flavescens Stone 1903 

DescripTion.—The largest species of the family Kinosternidae found 
in North America, the carapace measuring up to 146 mm in length. Shell 
broad, greatly depressed, flat, often even-dished along the mid-dorsal line 
of the carapace. Carapace: first vertebral scute triangular, the apex 
(anterior margin) equal in length to the sides; truncate at the posterior 
margin. Second, third, and fourth vertebral scutes roughly hexagonal, 
with the anterior margin greater than the posterior. Fifth vertebral 
truncately triangular. First, second, and third costal scutes very large; 
the fourth conspicuously smaller. Marginals 22 in number, plus the 
nuchal. Nuchal scute very small. Ninth and tenth marginals conspicu- 
ously large, triangular, the apexes contiguous and the two scutes of 
equal height. Caudal marginals relatively small. This condition of the 
three pairs of posterior marginals is to be found in no other kinosternid. 
Scutes mostly smooth, with a slight tendency toward rugosity in the 
posterior region. Plastron large, and similar in type to that found in 


THE TURTLES OF ILLINOIS—CAHN 


wn 
N 


the K. subrubrum group. Gular large, unpaired, its length approximately 
equal to the interhumeral suture. Humerals roughly rectangular. Pec- 
torals triangular, the interpectoral suture very short (ct. Boulenger 
1889, p. 36). Abdominals nearly square, the wings grooved posteriorly. 
Femorals triangular, with a very short interfemoral suture, this suture 
approximately one-seventh of the interanal suture. Anals triangular, with 


PLATE 6.—Kinosternon flavescens: A, Adult, ventral view. B, Same individual, 
dorsal view. C, Newly hatched young, dorsal view (Oklahoma specimen). D, 
Adult, lateral view. 


58 ILLINOIS BIOLOGICAL MONOGRAPHS 


a long interanal suture, and with a conspicuous round-shouldered notch 
posteriorly. Considerable cartilaginous material is found along the pec- 
toral-abdominal and the interabdominal suture, and still more along the 
abdominal-femoral suture, the amount varying with the sex of the indi- 
vidual, being greater in males than in females. Axillary small; inguinal 
long and narrow, reaching to the seventh marginal. Head large and 
powerful. Top of head with a small bifurcated U-shaped nasal plate, the 
arms of the ‘‘U” following the dorsal rim of the orbit to its posterior 
margin. The shell of the upper jaw reaches the anterior ventral margin 
of the orbit, following half-way up it, but does not make contact with 
the nasal plate, leaving a fleshy bridge between the snout and the anterior 
dorsal margin of the orbit. Snout pointed. Upper jaw strongly hooked 
and with a prominent “first tooth.” Posterior to this the profile of the 
jaw appears as a curved blade without any further prominent “teeth.” 
Gular barbels prominent; second pair of barbels on the throat either 
inconspicuous, uni-lateral, or absent. Neck with but a few tubercles 
dorso-laterally and none ventrally. Horny scales on the wrist practically 
absent; inconspicuous. Claws on the fore limb strong, but highly 
graded as to length: the outer (fifth) is very small, the fourth twice its 
length, the third three times its length, the second four times its length, 
the first (inner) like the third. Posterior claws also graded, but to a much 
less extent. Tail long in the male, short in the female, but usually with 
a distinct terminal nail or “claw” in both sexes. Apparently this nail is 
in rare cases absent. 


CoLoratTion.—Carapace olive green, uniform in tone, the sutures 
being finely edged with black, which is increasingly inconspicuous in the 
older and larger specimens, yet wanting in newly hatched young. This 
black margin tends in some specimens to overlap the suture as in K. 
subrubrum hippocrepis, while in others it lies as the posterior boundary 
of the anterior scute, much as in K. subrubrum subrubrum. Plastron 
light in color, yellowish, with a tendency toward brown. Soft parts gray- 
green, darker above and lighter beneath; unmarked. Throat, sides of 
neck, and head yellow. Head without markings of any kind. Jaws horn 
colored, mottled with dark olive. 


Younc.—The young exhibit the general configuration and coloration 
of the adult, but are much more circular in form. The most conspicuous 
difference lies in the condition exhibited by the marginals in newly 
hatched and very young individuals. Whereas in the adult the ninth 
and tenth are conspicuously large and elevated, in very young individ- 
uals (32 mm) this is not the case, these two scutes being actually smaller 
and less elevated than the seventh and eighth. In young having a cara- 
pace 67 mm in length the conspicuousness of the ninth and tenth 
marginals is already well established and typical of the adult condition. 


THE TURTLES OF ILLINOIS—CAHN 59 


A further feature of the young lies in the fact that the costal and ver- 
tebral scutes bear what appears to be a broad band impressed along the 


Piate 7.—Kinosternon flavescens: A, Three-quarters posterior view of an 
adult, to show the relative size and shape of the last three marginal scutes. B, 
Adult male, ventral view. C, Adult female, ventral view. 


60 ILLINOIS BIOLOGICAL MONOGRAPHS 


anterior and lateral margins of the scutes, this band being separated 
from the rest of the scute by a tiny ridge, giving the scutes an appearance 
of being slightly rugous. (The above descriptions are taken from speci- 
mens 3£3642, 4617, and 9958, Museum of Zoology, University of Okla- 
homa, kindly loaned by Dr. A. I. Ortenburger). 


Sex DIFFERENTIATION.—The typical kinosternid features hold true 
in this species in so far as sexual dimorphism is concerned. In males, the 
tail is much longer than in females. The beak of the upper jaw is more 
pronounced in males than in females. The male has “stridulating organs” 
on the inner surface of the hind legs well developed in the form of a 
group of small, but strong, horny tubercles, which are absent in the 
females. Males are considerably larger than females. 


GEOGRAPHICAL DistRiBuTION.—Kinosternon flavescens is distinctly a 
western and southwestern species, the occurrence of which within the 
limits of Illinois is, to say the least, surprising. Stejneger and Barbour 
(1923) give its range as “Texas, north to Kansas and Colorado, west to 
Arizona.” Yarrow (1882) reports it from Fort Yuma, California, Fort 
Union, New Mexico, and Utah; 
Boulenger (1889) from Arkansas, 
Western Texas, and the Gila 
River; Siebenrock (1907) from 
Arkansas, Texas, and Arizona. 
Ortenburger and Freeman (1930) 
report that “without question this 
is one of our commonest, if not 
the commonest turtle in Oklahoma 
wherever water is available.” 


Itiinors Recorps.—Until the 
report by Cahn (1931) of the 
finding of this species in Illinois, 
it was unrecorded from the state. 
At the time of publication of that 
paper, five specimens only had 
been taken, all of these on the 
Illinois River at Meredosia Bay. 
These were taken by Dr. David 
H. Thompson of the Illinois State 
Natural History Survey, who re- 
ported that he had seen probably 
twenty to twenty-five additional 
specimens on the Illinois River 
between Meredosia and Peoria 
a distance of approximately 90 Map 4.—Kinosternon flavescens. 


THE TURTLES OF ILLINOIS—CAHN 61 


miles by river. During the summer of 1931 Mr. Joe Combs, working 
and collecting for the writer at Meredosia Bay, was able to obtain an 
additional 11 specimens, comprising both sexes, so that the number now 
on hand from Illinois totals 16. One of these has been deposited in the 
United States National Museum, #83190. 


Hasitat.—From all reports, Kinosternon flavescens is preeminently a 
pond turtle. In western Oklahoma, where it is one of the commonest of 
the turtles found, it inhabits roadside ditches and cattle ponds (often 
artificially constructed) of almost any size. So common is it in this 
western region that Ortenburger finds one or more per each hundred or 
two hundred feet of roadside ditch. They are highly aquatic, as is the 
case in other kinosternid species, and seem most at home in the muddy 
bottoms of shallow ponds, where they often lie partially buried in the soft 
material. The same applies to the species as found in Illinois. While the 
five original specimens were taken from hoop nets used by fishermen to 
catch catfish, ten of the remaining eleven specimens were all taken from 
a single small, muddy overflow pond which had but a few inches of 
water in it. This temporary pond was but a hundred feet from the river, 
yet had no connection with it. The turtles must therefore have chosen 
to inhabit it rather than the river, and they were found lying in the soft 
mud at the bottom, apparently quite content. The sixteenth specimen 
was found walking down a sandy path near the edge of the river. 

Unfortunately, we can give almost no information concerning this 
interesting turtle. Of the habits, nest, eggs, and incubation periods noth- 
ing is known, so far as I have been able to ascertain. Agassiz (1857) 
figures the newly hatched young, but not the egg, and gives no informa- 
tion or discussion of the species. It was hoped that some light might be 
thrown on these obscure phases of its life history as a result of the work 
of the summer of 1931, but the field work yielded no results in this 


TABLE 5.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Kinosternon flavescens 
(Measurements in millimeters; weight in grams) 


Carapace Plastron Tail 
Specimen Head |__| Weight | Sex 
Length} Width | Length | Width | Depth Total A-T 

Ler lcieietereie costae 146 98 1241 86 45 30 58 22 483 ef 
DA Sein Poe ON 138 98 114 79 43 30 Dil 20 422 fof 
RS erecvinutstasnecoe ese 128 90 108 75 42 27 53 18 391 ek 
SD otess iaenstacavets ts 140 99 121 83 45 30 54 18 446 Co 
Diane tatehpacusielaycte 132 94 118 V7 43 28 55 19 412 (oy 
Omalonismyerteas sonic 105 78 93 60 41 23 51 16 253 fof 
iE ees 132 93 114 76 50 29 56 18 401 fo 
Savin oan sess 5S 137 97 agile, 84 51 30 55 19 457 fou 
Oey oistateistsherate ote 137 94 120 83 53 29 54 19 419 fo 
DO ae cducsegeicse.e 2 a 135 94 104 75 49 31 53 dif 412 foil 
rear aveperee 0 3say 142 97 120 75 49 30 56 20 461 fof 
2 Giercsarapetarereekarers 142 97 120 73 48 31 54 20 450 ou 
WSistete sa crsrsvsis fevers 112 86 106 69 42 22 22 iB 296 g 


62 ILLINOIS BIOLOGICAL MONOGRAPHS 


direction. As a matter of fact it is interesting to note that of the 16 
specimens taken to date, fifteen are males. Whether or not this pre- 
ponderance of males is of any significance in relation to the habits of the 
species is not at present clear. The single female was taken on June 20 
from the temporary pond previously mentioned. Dissection showed the 
ovary to be small, but it contained two ovarian eggs well along in their 
development and apparently to be laid in a month or so. The stomach 
contained a quantity of vegetable matter which apparently was either 
grass or some semi-aquatic plant having similarly slender leaves. 

Just how we are to explain the appearance of this species in a thriving 
condition so far removed from its hitherto known range is something 
of a problem. That they are thriving is indicated by the fact that the 
bigger specimens taken are larger than any loaned me from the region 
of their greatest abundance. Probably no river in the United States has 
been more thoroughly “worked” by zoologists than has the Illinois, par- 
ticularly at the very place from which these turtles came. The Illinois 
State Natural History Survey began its investigations here in the 1870's, 
and has continued almost without interruption to date. Garman, gather- 
ing material for the Survey, collected here, yet found no evidence of this 
species. It escaped the notice of the investigators who inspected hun- 
dreds of nets set by fishermen over a period of many years, and which 
caught thousands of turtles. True, these men were not interested in 
turtles, vet its peculiar form might well have attracted attention. Are 
we to conclude that it is a new arrival in the district, or that it is simply 
a rare species which has, somehow, been overlooked? Or are we to say 
that it is a “transplant” recently introduced or liberated in the vicinity? 
The latter view seems highly improbable in view of the numbers recorded 
and the abundance of the species once its optimum environment is located, 
not to mention the distribution over 90 miles of the river. The condition 
of the female indicates that the species is breeding, hence established. 
About all that can be said is that the turtle is rare, that its distribution in 
the state is limited according to our present knowledge to the middle 
reaches of the Illinois River, and that it is an established species. 


Kinosternon subrubrum subrubrum (Lacépéde) 


Testudo subrubra Lacépéde 1788 Kinosternon punctatum Gray 1870 
Testudo pensylvanica Gmelin 1788 Thyrosternum pensylvanicum Agassiz 
Emys pensylvanica Schweigger 1814 1857 

Terrapene pensylvanica Merrem 1820 Swanka fasciata Gray 1872 

Cistudo pensylvanica Say 1825 Cinosternum pensylvanicum Boulenger 
Kinosternon pensylvanicum Bell 1825 1917 

Kinosternon oblongum Gray 1844 Kinosternon subrubrum subrubrum 


Kinosternon doubledayi Gray 1872 Stejneger & Barbour 1917 


THE TURTLES OF ILLINOIS—CAHN 63 


DescripTion.—Carapace rather elongate and narrow; smooth, un- 
keeled. The curvature of the shell is gradual at the anterior end, appear- 
ing to be somewhat depressed, and abrupt posteriorly beginning with the 
fourth vertebral scute; the fifth vertebral is nearly vertical. The anterior 
margin of the carapace is almost truncate, the posterior oval in outline. 
Costal scutes very large, transverse in their major axis. Vertebral scutes 
relatively small; marginals very small and elongate. The first vertebral 


PLate 8.—Kinosternon subrubrum subrubrum: A, Adult, ventral view. B, 
Dorsal view of the same individual. C, Three-quarters posterior view, to show 
the relative size and shape of the last three marginal scutes. D, Adult, lateral view. 


64 ILLINOIS BIOLOGICAL MONOGRAPHS 


scute is triangular, truncate at its apex, which is directed posteriorly ; 
the second, third, and fourth are roughly hexagonal; the fifth pentagonal. 
Costal scutes in a graded series, the first being the largest. The gular is 
very small, wider in front than behind, and larger in its ventral aspect 
than in its dorsal. Marginals entire, though occasionally showing a 
slightly sinuate condition, but never flaring. The tenth marginal is much 
enlarged, encroaching into the posterior margin of the fourth costal scute. 
The plastron is acutely rounded in its anterior border and shallowly 
notched posteriorly ; both anterior and posterior lobes are movable. Gular 
scute single, triangular, and less than half the length of the anterior 
plastral lobe. Humeral scutes with their median suture are very short, 
so that the humerals almost meet the abdominals; the pectorals are not 
involved in the bridge. Abdominals almost square, their wings forming 
the major part of the bridge. These wings bear a posterior groove and 
exhibit a prominent anterior shoulder. Femorals triangular, the apex 
posterior-lateral, and with a very short interfemoral suture. The anals 
are tringular, with the apex directed anteriorly. “Axillary very small, 
elongate ; inguinal large. The axillary and inguinal scutes meet between 
the wings of the abdominals and the marginals, to help complete the 
bridge. In some specimens the plastral scutes are rough and exhibit a 
series of concentric striae; in others these striae are worn down, leaving 
the plastron smooth. Head large, the snout somewhat attenuated; jaws 
strong, the upper hooked. A pair of barbels under the chin, and a 
second pair farther back on the throat. Eyes located well forward. 
Limbs short but strong, the anterior with several transverse scales on 
the dorsal surface, and a few small scales on the palm. Posterior limbs 
without the dorsal scales, but exhibiting the palmar series. Digits 5-4; 
claws short, stout, curved. Tail short. Skin finely tuberculate. 


CoLoration.—The carapace is uniformly olive brown, each scute 
with a narrow black margin along the suture. This black band is con- 
fined to the scute anterior to the suture, not overlapping the suture as in 
the case of Kinosternon subrubrum hippocrepis. The plastron varies 
from brown to yellow or horn-color, the brown apparently wearing off 
with age, but persisting along the sutures. The head is olive brown, with 
distinct yellow mottlings in the form or irregular lines and amoeboid 
spots. Under side of the head yellow with olive-brown reticulations and 
spots, becoming indistinct on the neck. Remaining soft parts grayish 
brown. Iris chestnut brown. 

YounG.—The young conform to the general plan of the adult, except 
that the carapace often exhibits a trace of three small keels, one row on 
the vertebral scutes and one row on each of the costal series. 


Sex DIrFeReNTIATION.—The males bear a small patch of horny, 
keeled tubercles on the posterior side of the leg, and another similar 


THE TURTLES OF ILLINOIS—CAHN 65 


patch below the thigh. The male has the tail terminating in a horny, 
nail-like claw. 

GEOGRAPHICAL DistRIBUTION.—The range of Kinosternon subrubrum 
subrubrum can at present be given best only in general terms, and may 
be said to include the eastern portion of the United States from New 
York, where it is very rare, westward to Illinois. Hay (1892) reports it 
from Knox county (southwestern) and from Terre Haute (westcentral ) 
Indiana under the name of K. pensylvanicum. It extends from these 
more northern states southward to include Tennessee (Blanchard 1922) 
and Louisiana (Viosca 1931), but seems not to reach peninsular 
Florida. Under the older name of Kinosternon pensylvanicum (and 
the various spellings of both generic and specific names) is included 
both subrubrum subrubrum and subrubrum hippocrepis, and since the 
earlier investigators failed to recognize the two closely related forms 
and did not differentiate between them, it is very difficult at the present 
time to delimit exactly either form because of this inclusion. 


Itttnors Recorps.—Under the 
name of Cinosternum pensylvani- 
cum, this form is included in the 
herpetology of Illinois by Garman 
(1892). At least it is presumed 
by the writer that the form to 
which Garman has reference is K. 
subrubrum subrubrum, for the 
Garman collection of turtles has 
completely disappeared, and it is 
impossible now to check on his 
specimens. This must not be con- 
strued as a reflection upon the ex- 
cellent work of Garman, but with- 
out the original material for 
study and verification, it is dif- 
ficult to do more than interpret his 
designation. As to the occurrence 
of subrubrum in Illinois, Garman 
says: “Southern Illinois, not rare; 
Peoria (Brendel); Mt. Carmel, 
common (Ridgway).”’ The only 
specimen which the present writer 
has from Illinois is a very typical 
shell found near Cairo in 1930. 
The turtle was found dead in a 
swamp north of Cairo, ina locality 
to which it could not possibly have 
been washed by floods of the Mis- 


er eae Map 5.—Kinosternon subrubrum 
sissipp1 River. subrubrum. 


66 ILLINOIS BIOLOGICAL MONOGRAPHS 


Hapirat.—The discussion which follows is based of necessity upon 
our knowledge of the species as found in localities other tHwn Illinois. 
K. subrubrum subrubrum is found in ponds, muddy ditches, and weedy 
lakes. Its general environmental preferences are rather similar to those 
of Sternotherus odoratus, although it is considerably less aquatic than 
that species. It is normally absent from streams with gravel bottom and 
current, preferring the mud in which it can bury itself for protection, 
and the quiet waters more often associated with mud conditions. It is 
not adverse to journeys upon land, and may be found quite a distance 
from its usual abode during the summer. In this respect it differs 
markedly from S. odoratus. 


Hasits.—Unlike the other Illinois species of the family, this form 
exhibits a tendency to appear frequently on the dry land, wandering away 
from the water for considerable distances. Whereas the other species 
hibernate in the mud at the bottom of the ponds, K. subrubrum sub- 
rubrum has often been found buried six to twelve inches down in the 
dry soil quite removed from the proximity of water. Other burrows, 
apparently in dry soil, are found to terminate in a small chamber close 
to the ground-water level, in which the bottom at least is wet and 
muddy. When the turtles emerge from their burrows after hibernation, 
they are very sluggish, rather emaciated, and heavily caked with dried 
mud, 

This turtle, however, spends most of its time in water, where it 
wanders about in search of food much as does S. odoratus. It is a strong 
swimmer, capable of making rapid progress with this method of loco- 
motion. To quote Agassiz (1857): “The slender legs are fitted for travel- 
ing on dry land, but easily carry the body through the water over its bot- 
tom. When surprised away from the water, the animal seeks the nearest 
hiding-place ; if danger is close at hand, it quickly withdraws the exposed 
parts into the shield, and, if pressed still farther, it resorts at last to 
biting, not throwing the head quickly and forcibly out as the Chelydoidae 
do, but stretching it out rather slowly toward the assailant, and then 
snapping the jaws forcibly upon it.” Although this quotation is applied 
by Agassiz to kinosternid turtles in general, it fits admirably the observed 
behavior of the present species. While not as vicious as Sternotherus 
odoratus, this species is capable of biting when occasion seems to demand, 
preferring, however to retreat within its shell. After the head is with- 
drawn, K. subrubrum subrubrum has a greater degree of protection, due 
to the larger size of the plastral element, and to the fact that the 
plastral lobes more completely close the ventral aperture. 

When disturbed, this musk turtle emits the same type of musky 
odor which is characteristic of the family, though to a much less degree 
than in S. odoratus. In fact, the writer has found the odor emitted by 


THE TURTLES OF ILLINOIS—CAHN 67 


specimens in the laboratory to be very weak and not at all disagreeable. 
It is doubtful whether this excretion is of any protective value. 


NestinG Hasits.—The writer has never seen the nest of this species, 
and there is little information in the literature describing the nesting 
habits. Presumably they are not very different from those of Sterno- 
therus odoratus. Brimley (1903) reports that the eggs are sometimes 
found in holes in the banks of streams, and that they are frequently 
plowed up in low ground. 


Eccs.—The eggs of this species resemble those of S. odoratus so 
closely as to be almost indistinguishable from them, though they are a 
trifle smaller in size. They are an elongated oval in shape, with blunt 
ends, and are covered with a shell of remarkable thickness for so smal! 
an egg. This shell is of very fine texture, perfectly smooth, due to a slight 
glaze, and exceedingly brittle. The eggs number from two to five in a 
clutch, three being the usual number deposited by one female. The aver- 
age size of 7 eggs measured by the writer shows them to be 27.4 mm by 
14.3 mm. Nothing is known of the period of incubation. 

Foop Hasits.—This is largely a carnivorous species, which is re- 
ported to feed upon fish and insects. A specimen shipped to me from 
Louisiana had the remains of earthworms and five beetle wing coverts 
in the stomach. Kept in the laboratory, they seem entirely satisfied with 
a diet of chopped meat. In nature, they are reported to nibble daintily at 
the baited hooks dangled by fishermen for more valued prizes. 


Economic ImportaNce.—The small size and the musky flavor of 
this little turtle makes it unfitted for human consumption. It is very 
doubtful whether the food habits of the species render it either an 
economic asset or liability. 


Parasites.—When compared with specimens of S. odoratus, this 
species is much less parasitized by leeches, due probably to its more 
frequent journeys to land. The alimentary canal is far freer of internal 
parasites; though the writer has taken nematodes on several occasions 
from the pyloric end of the stomach. 


FAMILY TESTUDINIDAE 


Testudinidae, Emydidae (part) Gray 1825; Bell 1828; Ritgen 1828 

Tylopodes, Steganopodes (part) Wagler 1830 

Testudinidae, Emydae (part) Gray 1831 

Chersites, Elodites Cryptoderes (part) Duméril & Bibron 1835 

Emydoidae, Nectemydoidae, Deirochelyoidae, Evemydoidae, Clemmydoidae, Cistu- 
dinina, Testudinina Agassiz 1857 

Chersemydina (part) Strauch 1862 

Testudinidae, Cistudinidae, Emydidae, Malaclemmydae, Pseudemydae, Bataguridae 
Gray 1870 

Testudinidae, Emydidae (part) Cistudinidae Cope 1882 


68 ILLINOIS BIOLOGICAL MONOGRAPHS 


Chersemyda (part) Strauch 1890 
Cryptoderinea (part) Vaillant 1894 
Emydinae Siebenrock 1909 

ExternaL Dracnosis.—Turtles having a bony shell, covered with 
epidermal scutes, which is moderately (never greatly) depressed, or 
(extralimital) highly arched. Carapace oval, broadest posteriorly, and 
highest at about the middle, from which the shell slopes in all directions 
to flaring marginals. Scutes of carapace: 5 vertebrals, 8 costals, 25 mar- 
ginals. Plastron with 12 (rarely 11) scutes; axillary and inguinal ele- 
ments usually present. Anterior lobe of plastron (and rarely also the 
posterior lobe) in some species movable on a transverse hinge capable 
of closing the aperture. Toes broadly webbed in aquatic species and im- 
perfectly webbed in terrestrial forms. Head of moderate size, covered 
with smooth skin, and retractile within the shell. Jaws naked. Digits 
moderate to short and with either 4 or 5 (extralimital exceptions) claws. 
Tail short. 


OsteotocicaL D1aGNnosis.—Nuchal plate without costiform processes. 
Plastron composed of 9 dermal elements, the entoplastron present. 
Caudal vertebrae procoelous. Temporal arch usually present; no parieto- 
squamosal arch. Phalanges with condyles. Neck completely retractile. 


Genus CLteMMys RITGEN 


Emys (part) Duméril 1806 Nanemys Agassiz 1857 
Chersine (part) Merrem 1820 Calemys Agassiz 1857 
Clemmys Ritgen 1828 Glyptemys Agassiz 1857 
Clemmys (part) Wagler 1830 Actinemys Agassiz 1857 
Terrapene (part) Bonaparte 1830 Mauremys Gray 1869 
Chelopus Rafinesque 1832; Cope (part) Sacalia Gray 1869 
1865 Emmenia Gray 1869 

Geoclemys (part) Gray 1855 Eryma Gray 1869 


Shell moderately depressed. Axillary and inguinal elements well de- 
veloped, reaching exactly to the first and fifth costal scutes; bridge wide. 
Alveolar surfaces of the jaws narrow and without a sharp medial ridge. 
Endoplastron with a suture between the humeral and pectoral bones. 
Choanae located between the eyes; skull without a dorsal medial ridge, 
and with a bony temporal arch present. Neck fairly long. Tail stout in 
the adult. Digits fairly well webbed. 


Clemmys guttata (Schneider) 
(Spotted turtle; speckled turtle) 


Testudo guttata Schneider 1792 Nanemys guttata Agassiz 1857 
Testudo punctata Schoepff 1792 Clemmys guttata Strauch 1862 
Emys guttata Schweigger 1814 Geoclemmys sebae Gray 1869 
Emys punctata Merrem 1820 Geoclemys guttata Gray 1870 


Terrapene punctata Bonaparte 1830 Chelopus guttatus Cope 1875 


THE TURTLES OF ILLINOIS—CAHN 69 


DEscRIPTION.—Shell oval, somewhat depressed. It is wider posteri- 
orly and without a trace of a vertebral keel in the adult. First vertebral 
scute pentagonal, shield-shaped, the remaining vertebrals hexagonal. 
The second vertebral with the anterior border shorter than the posterior ; 
third vertebral with the anterior and posterior margins approximately 


PLATE 9.—Clemmys guttata: A, Adult, ventral view. B, Adult, dorsal view. C, 
Adult, lateral view. D, Head study of an adult. E, Newly hatched young, ventral 
view. F, Same individual, dorsal view. 


70 ILLINOIS BIOLOGICAL MONOGRAPHS 


equal in length. The fourth vertebral has its posterior margin only a 
trifle over one-half the length of the anterior border. In the costal series 
the first scute is the largest, but the second the widest; the first tends 
toward the triangular, though it is a trapezium, while the remaining are 
rectangular, the posterior scute tending toward square. The fourth 
costal is the smallest of the series. Nuchal long and exceedingly slender. 
Outer border of the marginals entire, not emarginate or serrate, though 
there is a shallow notch between the caudal marginals. There is a 
tendency toward sculpturing or rugosity on the scutes of the carapace. 
Plastron large, filling most of the aperture, the posterior lobe more than 
three-quarters the width of the carapace. The anterior lobe is truncate 
and without a movable hinge. Gulars sharply triangular. Humerals 
triangular, the interhumeral suture being very short, so that the posterior 
angles of the gulars almost touch the pectorals. Pectoral scutes rectangu- 
lar. The abdominals are the largest of the plastral elements and, while 
rectangular are approaching the square. Femorals approaching trian- 
gular, the interfemoral suture being short and from two to three times 
the length of the interhumeral suture. Anal scutes large, the interanal 
suture usually a trifle longer than the interabdominal suture; a shallow 
notch exists between the posterior margin of the anals. Gulars usually 
with fine longitudinal striations. The remaining plastral elements tend 
to have concentric striations which are markedly angular in character 
centering about the posterior lateral angle of each scute; in old speci- 
mens, however, these striations are likely to be worn away. The bridge 
is rather narrow, approximately one-half the width of the posterior lobe, 
and involves the full width of the abdominals and the posterior half of 
the pectorals. Axillaries and inguinals absent, or very small and rudi- 
mentary. Head moderate to small, covered with a tightly drawn and 
perfectly smooth skin. Snout blunt, the upper jaw with a deep median 
notch and with the alveolar surface very narrow. Lower jaw with a wide 
sheath externally, and with a sharp, upward hook. Skin of the neck 
finely granular. Legs and feet covered with scales, those on the anterior 
face of the limbs large and overlapping. Feet rather small, imperfectly 
webbed, the toes with short claws. All 5 of the digits of the fore limb 
with claws; hind limb with only 3 digits bearing claws. Tail short. 


CoLoraTion.—Carapace uniformly black, with an occasional tendency 
toward rust. Each scute bears from one to ten or more round, bright 
orange-yellow spots. The tendency is for each of the marginals to bear 
a single round spot, but often more than one is present on the scute. 
The plastron is mostly black, and is blotched with orange. Head and neck 
black, dotted dorsally with orange, and with a large orange blotch just 
above the ear; ventral surface mottled with orange and with a tendency 
toward a lateral stripe extending backward from the angle of the jaw 


THE TURTLES OF ILLINOIS—CAHN 71 


(see discussion of color in re sex differentiation). Limbs black above, 
with orange dots, the orange predominating ventrally. Tail black, with 
a few small orange dots dorsally, blending into orange around the anus. 


Younc.—The very young exhibit a trace of a vertebral keel, which 
entirely disappears with age. Each scute of the vertebral and costal 
series bears but a single yellow to orange spot, while on many of the 
marginals the dorsal spot is absent. With increasing age, other spots 
appear on the carapace as well as upon those marginals which originally 
did not possess a spot. 


Sex DIFFERENTIATION.—In the male, the plastron is somewhat 
dished or concave in the central area, while in the female this concavity 
is absent. While the tail is about the same length in both sexes, the 
anus of the male is placed in a position to bring it beyond the edge of 
the carapace, while in the female it is under the carapace. Yerkes (1905) 
has pointed out that, although the females are slightly smaller than are 
the males, they bear about 15 per cent more spots on the scutes of the 
carapace, the average number for males being 60, for females 69. The 
concavity of the plastron of the male and the position of the anus are 
listed by Blake (1921), who also gives the following sex distinguishing 
features: (1) The horny part (sheath) of the jaw of the male is dusky, 
of the female pale yellow. (2) The female has a conspicuous yellow or 
orange mandibular stripe reaching half the length of the neck, while the 
male has but a few spots or at most a very weak streak here. (3) The 
throat of the male is black, with few yellow specks, while the female 
has the throat heavily streaked and spotted with yellow. (4) The female 
has a well developed supra-auricular yellow line, or a series of yellow 
spots, while in the male this line is poorly developed. (5) In the female 
there are a few yellow spots on the crown in front of the eyes, while in 
the male there are but one or two such spots. 


GEOGRAPHICAL DistRIBUTION.—The spotted turtle, Clemmys guttata, 
is an eastern species, the western limit of whose range lies in Wisconsin 
and Illinois. It is common throughout the Atlantic States from Maine 
to northern Florida. It is less common in the northern reaches of its 
range in the New England states, but is a common species in the southern 
members of this group. Morse (1904) reports that, while not rare in 
Ohio, it is found over most of the state, but is not a common turtle; 
Ruthven et al (1912) report it from most of the counties composing the 
southern third of Michigan. In Indiana, Hay (1892) reports it from a 
number of localities in the northern part of that state, including Lake 
Maxinkuckee, and in his “Preliminary Catalogue” he reports it as being 
“rather common about La Porte and in the marshes of the Kankakee 
River.” The westernmost records lie in southern Wisconsin. For this 
state Higley (1889) reports it from Walworth county, Beloit, Madison, 


72 ILLINOIS BIOLOGICAL MONOGRAPHS 


and Eau Claire; to these records Pope and Dickinson (1928) add speci- 
mens from Waukesha County and from Fond du Lac County, and Cahn 
(1929) adds a second record from Waukesha County. 


Irttnots Recorps.—Clemmys guttata has not previously been re- 
ported from Illinois, and no mention of it occurs in the literature of this 
state. The University of Illinois now has in its collection two specimens 
of the species collected by the writer in June, 1927, in a small pond just 
beyond the Illinois end of Wolf Lake, Cook County. So far as the writer 
knows, these constitute the only Hlinois records. 


Hasitat.—The spotted turtle 
is an aquatic species which, how- 
ever, spends a considerable 
amount of its time on land, often 
quite away from the water. Its 
choice of habitat lies with swamps, 
small weedy ponds, and streams, 
and in the east even salt marshes. 
Above all else it prefers a swamp 
or a pond with a muddy bottom 
in which it can bury itself, and 
avoids streams with a marked cur- 
rent. As between lakes and 
streams, its preference is for lakes 
and shallow ponds. When the 
spirit moves—which may be at 
any time during the summer—the 
turtle undertakes overland jour- 
neys of considerable length, wan- 
dering about in sphagnum bogs or 
out into the open fields. These 
journeys are not necessarily as- 
sociated with the nesting instinct 
or with the drying up of the 
ponds; they seem, rather, to be 
the gratification of a “wanderlust”’ 
‘which frequently attacks the Map 6.—Clemmys guttata. 
turtles and drives them afield. 


Haspits.—These turtles exhibit a very marked difference in some of 
their habits when their behavior in water is compared with that on land. 
In the water they are exceedingly shy and wary. Sunning themselves 
on a protruding log out in the pond, or in the midst of a clump of half- 
submerged grass, the first sign or suspicion of danger sends them scoot- 
ing off their perch into the protection of the mud and aquatic vegetation. 


THE TURTLES OF ILLINOIS—CAHN 73 


A desirable log may have turtles piled on top of it in two or three layers, 
the late arrivals climbing up on the backs of those already enjoying the 
sunshine. Experiments carried out by the writer years ago with this 
species in Massachusetts, showed that individuals have certain favorite 
perches and that they tend to return to the same sunning place day after 
day throughout the season, indicating at the same time that while in the 
water they are not given particularly to wandering far from their 
favorite spot. On land, however, the turtle is quite solitary in its habits, 
and seldom is more than a single individual found. The impulse which 
sets them wandering seems to destroy at the same time the gregarious 
instinct, and their rambles on shore are quite solitary. The timid dispo- 
sition persists on Jand, and the turtle withdraws its head quickly when 
danger threatens and is very slow about resuming its progress when the 
crisis is over. Just why this species should be so shy is a problem, for 
it has almost no enemies outside of animals like skunks which dig up its 
eggs. Associated with this timidity there is no trace of aggressiveness 
or viciousness under any circumstances; no matter how much the turtle 
is teased or annoyed it never snaps. In captivity this timidness persists 
for a long time, but eventually at least partially wears off and the crea- 
ture makes a very good aquarium or terrarium pet. 

Nestinc Hasits.—The spotted turtle lays its eggs between the mid- 
dle of June and the first of July over most of its range. Copulation, 
according to Babcock (1919), occurs in the water. A true amplexus takes 
place, the male embracing the female so tightly that the pair can be 
raised out of water by lifting the male, which is on top. The female 
leaves the water in order to find the proper place for her nest, and often 
wanders quite a distance from the water’s edge. The site selected may 
be either in sand or in dirt, but it is always in material of fine texture. 
The hole is dug with the hind legs entirely, and is a vertical pit from 
two to four inches deep, and without any notable terminal chamber. 
The time required is upward of half an hour, depending upon the type 
of material being excavated. Standing about vertical in the hole, with 
little more than the head and shoulders protruding, the turtle lays her 
complement of eggs. When oviposition is completed, the female crawls 
out of the hole, and fills up the cavity with the excavated dirt, using, 
again, only the hind legs. If the turtle is disturbed while digging the 
hole, she retreats within the shell and patiently waits until things quiet 
down; she seldom will withdraw from the site of operations or give up 
the hole she has begun. Agassiz (1857) states that the spotted turtle 
lays her eggs in the evening between four and eight-thirty. This unusual 
time of day for a turtle to lay—unusual because most other species lay 
earlier in the day—may well be the result of the timid disposition pos- 
sessed by the species. 


74 ILLINOIS BIOLOGICAL MONOGRAPHS 


Eccs.—The eggs usually number either two or three, very rarely four. 
and in shape are an elongated ellipse with sharply curved ends. They are 
covered with a tough, white membranous shell. The size varies closely 
around 30 mm by 16 mm. 


IncusatTion.—Babcock (1919) publishes some interesting data on the 
period of incubation. The eggs in question were laid on June 15, on 
which date they were buried in sand. They hatched on September 6, 
giving an incubation period of 82 days for this individual. However, 
nothing is said as to the conditions under which these eggs were kept— 
whether natural or artificial, whether indoors or out—so that there is no 
way of telling whether this is a normal incubation period for the species 
or whether the regular interval has been interfered with. Upon hatching, 
the young are possessed of an “egg tooth,’ a horny tubercle on the tip 
of the snout, which is the pick used by the baby in breaking the shell 
when it is ready to emerge. This tubercle disappears at the end of the 
first week, and the stump of the umbilical cord disappears at about the 
same time, though the umbilicus remains visible for a long time there- 
after. The young are very active on hatching and are good climbers. 
The rate of growth of the carapace, as reported by Babcock, is as fol- 
lows: at hatching, 26 mm; first month, 30 mm; second month, 32 mm; 
fifth month, 32 mm. On the tenth day the young were fed angle worms, 
but at the end of the second month they ceased eating and did not survive 
the winter. Perhaps the slow rate of growth following the first month 
after hatching (October to February), outside of the fact that the young 
refused to eat, is associated with the period of normal hibernation. 


Foop Hagirs.—Clemmys guttata is largely a carnivorous species, 
although vegetable matter figures in its diet to a small degree. Surface 
(1908), who has published the only comprehensive account of the food 
habits of turtles, says, in regard to twenty-seven specimens examined: 
“Only one-ninth of the individual specimens had eaten vegetable matter, 
and in fact there was very little plant tissue found in the stomachs, while 
all of them contained animal matter. Not only is it remarkable that all 
contained animal tissue, but also that all of them had eaten insects.” A 
list of the animal forms found includes: worms, slugs, snails, small 
crustaceans, crayfish, millipedes, spiders, and insects representative of 
the Ephimerida, Plecoptera, Odonata, Hemiptera, Neuroptera, Lepidop- 
tera, Coleoptera, Diptera, and Hymenoptera. Many of the insects eaten 
are not aquatic species, and these probably were picked up from the 
surface of the water rather than gathered during the terrestrial journeys. 
Like most aquatic turtles, the spotted turtle apparently eats and swallows 
only under water, and hence it appears doubtful that much material is 
consumed while on land. Hay reports it as eating tadpoles and small 
frogs. They also eat angleworms and soft-bodied forms of insect larvae. 


THE TURTLES OF ILLINOIS--CAHN 75 


Economic ImporTANCE.—Probably none so far as man is concerned. 
The insects eaten represent few that are either a benefit or a detriment 
to man and, since the turtle is too small to be considered as a table 
delicacy, the spotted turtle has no dollar and cents value to man. It is 
not a scavenger. 

Parasites.—Because of its habitual visits to the land and on account 
of its habit of sunning itself for long hours out of water, this species is 
less infected with leeches than most of our water turtles, though leeches 
are usually abundant in its favored environment. 


TABLE 6.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Clemmys guttata 
(Measurements in millimeters) 


; Carapace Plastron Tail 
Specimen ese Sex 
is Length | Width Length | Width | Depth Total | A-T 
| 
Whe as cee 109 | 87 | 99 | 71 | 40 | 16 | 26 | 20 9 
Dr eeexaheittone 114 76 95 | 68 | 40 16 31 | 25 g 
GeNus EmMys DuUMERIL 
Emys (part) Duméril 1806 Emyoidea Gray 1870 
Terrapene (part) Bell 1825 Emys plus Emyoidea Baur 1889 
Cistudo (part) Gray 1831 Neoemys Lindholm 1929 


Lutremys Gray 1855 

Plastron united to the carapace by a ligamentous attachment. Plastron 
divided by a ligamentous hinge between the pectoral and abdominal 
scutes (between the hyosternal and hyposternal elements of the endo- 
skeleton) into two movable lobes; hind lobe truncate posteriorly or with 
but a shallow notch, and smaller than the aperture. Humero-pectoral 
suture overlying the entoplastron. Skull with a bony temporal arch; 
alveolar surfaces of the jaws without a median ridge; choanae between 
the eyes very large; dorsal surface of the head covered with undivided 
skin and without plates of any kind. Webs of feet extending to the claws. 


Emys blandingu (Holbrook) 
(Blanding’s turtle; glass turtle) 


Cistuda blandingiu Holbrook 1838 Emys blandingu Strauch 1862 

Lutremys meleagris LeConte 1854 Emydoidea blandingu Gray 1870 

Emys meleagris Agassiz 1857 Neoemys blandingti Lindholm 1929 

Description.—The following description is taken from an exception- 
ally beautiful and unusually large specimen (carapace length, 240 mm). 
Shell oblong, moderately high but with the carapace flat dorsally, not 
arched or domed. Vertebral scutes large and wide. First vertebral 


76 ILLINOIS BIOLOGICAL MONOGRAPHS 


pentagonal, the sum of the two anterior faces exceeding considerably the 
length of the posterior margin, and meeting these borders at the median 
point in such a wide obtuse angle as to approach a straight line. Second, 
third, and fourth vertebrals much wider than long, especially the third; 
they are hexagonal, with the margins remarkably straight except for the 
anterior margin of the second and the posterior margin of the fourth, 
which are dished. The fifth vertebral is roughly triangular, all sides 
tending to curve outward. Costals large, tending toward the square. 
The second is the largest of the series; the fourth the smallest. There is 
a faint trace of rough, concentric striae at the outer margins of the scutes. 
Marginals 27 in number, with an even edge and no emarginations. There 
is a wide notch between the caudal marginals.. Nuchal long and very 
slender. Plastron distinctly oblong, truncate anteriorly and with the wide 
posterior emargination. It is composed of two lobes separated by a 
ligamentous hinge between the pectorals and abdominals. The posterior 
lobe is larger than the anterior and forms a ligamentous union with the 
marginals. Gulars sharply triangular. Humerals tend toward the trian- 
gular, but are truncate at the interhumeral suture, which is the shortest 
of the median articulations. Pectorals oblong or rectangular, as are the 
abdominals, and these two scutes are of very nearly the same size. 
Femorals much wider at their lateral margins than at the median suture, 
the posterior margins being curved to receive the anal scutes. Anals 
large and with a wide notch involving the entire posterior margin of the 
scute. Bridge very small indeed, and neither the pectoral nor abdominal 
scutes enter into its composition, it being represented by the ligamentous 
hinge between these elements and the marginals. Axillary very small 
and rudimentary; inguinal absent. The head is medium in size, flat 
dorsally, and covered with a smooth, tightly drawn skin. Cutting edge 
of the jaws almost straight, the upper with a wide but shallow median 
notch, the lower slightly upturned at the symphysis. Nostrils terminal 
and very close together. Neck long. Anterior limbs covered with strong, 
transverse scales on their anterior surface; digits five, the outer four with 
a strongly curved claw each, the fifth with but a rudimentary claw. Pos- 
terior limb larger than the anterior, covered with small scales, and with 
a projecting scale in place of the fifth digit; the remaining four digits 
with strongly curved claws. Tail long. 

CoLoration.—Carapace black or dark brown, with an intricate pattern 
of pale yellow spots and dashes radiating from a center at the posterior- 
median margin of the scute. The ground color of the vertebral series is 
black, while on the costal and marginals, particularly of the anterior 
two-thirds of the shell, the ground color is pale yellow with the intricate 
pattern in black upon it. These two arrangements of color intergrade 
imperceptibly at the vertebral-costal suture, and the carapace is much 


N 
N 


THE TURTLES OF ILLINOIS—CAHN 


Pirate 10.—Emys blandingii: A, A very large adult, ventral view. B, Same 
individual, dorsal view. C, Newly hatched young, lateral view. D, Immature 
individual, length three and a quarter inches, dorsal view. FE, Adult, lateral view. 
F, Head study of an adult. 


78 ILLINOIS BIOLOGICAL MONOGRAPHS 


lighter in color anteriorly than posteriorly. Plastron brownish yellow, 
blotched asymmetrically with great areas of black, these more pronounced 
at the lateral margin of the scutes. Head brownish olive above, finely 
mottled with irregular black lines, increasing in number posteriorly. Neck 
the same color as the head. Under parts of head and neck bright yellow. 
Upper jaw edged with black; lower jaw yellow. Legs dark above, lighter _ 
below, each scale tending to show a black spot. 

Few specimens that I have ever seen exhibit the perfection of mark- 
ings shown by the specimen just described. Often the markings on the 
carapace are obscure or even absent, as in a specimen taken at the 
southern tip of Lake Michigan, in which there is no trace of color 
markings whatsoever. This specimen is mahogany brown above, mottled 
irregularly with large areas of black. 

Younc.—The newly hatched young have apparently not been de- 
scribed in detail, and the writer failed in his efforts to obtain specimens 
for this purpose. Fowler (1906) says that they are “nearly circular and 
black.” Through the courtesy of Dr. Loveridge of the Museum of Com- 
parative Zoology, I have been able to borrow and to photograph their 
young specimen (341634) which is the original of Agassiz’ figures 20-22, 
plate + (1857). This little specimen is black, without markings on the 
carapace, the surface of which is granular; the plastron shows a central 
black area covering most of the surface, and a thin light peripheral area 
which probably was yellow. The plastron is one and one-half times the 
length of the tail. In the writer’s collection is a specimen with the cara- 
pace length 66 mm. A strong vertebral keel is evident, this highest on 
the fourth vertebral scute. Each dorsal scute has a posterior median 
area sharply demarked, and this exhibits a coarsely granular or porous 
surface. From this area, radiating streaks of yellow extend over the 
rest of the scute. The keel shows yellow areas. The plastron is yellow, 
with symmetrically placed areas of mahogany brown on each scute. In 
this specimen the wings of the pectoral and abdominal scutes form a short 
bridge terminating in the ligamentous hinge. Top of the head brown, 
spotted with yellow. 

Sex DIFFERENTIATION.—The tail of the male is longer than that of 
the female; in the male the shell is three times the length of the tail, or 
less, while in the female it is four times the length of the tail. 

GrocrapHic Disrripution.—Emys blandingti is a northern species 
with a range covering the northern quarter of the United States from 
New England on the east to Iowa and Minnesota on the west. While 
nowhere really abundant, the center of its abundance apparently lies in 
northern Indiana, from which region its numbers grow less as the range 
extends both east and west. Ditmars (1908) says that “eastward of the 
Central States it is comparatively rare, though the range extends into the 


THE TURTLES OF ILLINOIS—CAHN 79 


Alleghanean region and northeastward through Pennsylvania and New 
York into Massachusetts, Rhode Island and New Hampshire. The spe- 
cies does not occur near the coast regions of New York, Connecticut or 
New Jersey.” It is not common anywhere in New England, though there 
are scattered records over most of Massachusetts (Babcock). Surface 
(1908) considers it rare in Pennsylvania, and does not give any specific 
locality records. The first Pennsylvania record is that of Stewart (1928) 
for Lewisburg, and Netting (1932) 
adds two more; hence it must 
be considered rare in that state. 
Morse (1904) reports that it is 
nowhere abundant in Ohio, but 
says that it is found in streams 
flowing into Lake Erie and into 
the Ohio River. In Michigan, 
Ruthven et al (1912) report it 
from numerous counties in the 
southern part of that state. For 
Indiana, the state in which most 
authorities claim it 1s most com- 
mon, Hay (1892) says that it is 
found only in the lake region of 
the northern part of. that state, 
while in his “Preliminary Cata- 
logue” he says “it is found spar- 
ingly in northern Indiana.” For 
Wisconsin, Hoy (1883) reports 
it as “abundant on the prairies ;” 
Higley (1889) says it is common, 
and Pope and Dickinson (1928) 
record specimens from nine 
counties. In Towa, Blanchard 
(1922) reports a specimen from Map 7.—Emys blandingii. 
Dickinson County, mentioning 

that this record is the most westerly for the species, as well as the first for 
Iowa. It is reported by Nash from Ontario, Canada. 

Ittinots Recorps.—It is of especial interest to note that the type 
specimen was taken by Holbrook (1838) from “The Fox River” in 
Illinois, this being the only species of turtle the type specimen of which 
was taken in this state. Kennicott (1855) reports it as “common on the 
prairies.” Garman (1890) reports of this species that “‘as late as 1870 
it was rather common about water on the prairies of central Illinois; it 
is now very rare, only one example having been taken in the past six 


80 ILLINOIS BIOLOGICAL MONOGRAPHS 


years.’ Two years later Garman reports it as “throughout the state, 
commoner north; rare at present,” and records specimens only from 
Normal and Urbana. There is no evidence to bear out the statement that 
Emys blandingii has this distribution in the state—at least not at the 
present time—and it is extremely doubtful whether it ever occurred 
throughout the state. Hankinson (1917) reports it from Charleston, and 
Weed (1922) records it as “abundant” in the Chicago area. In the Field 
Museum are specimens from Lake Forest (#2435), Meredosia (3403, 
3427), Chicago (3247), as well as seven eggs from Waukegan (5953). 
The writer has examined specimens from the following Hlinois localities: 
Peoria, Havana, the Ilinois-Mississippi canal near Rock Island, Mere- 
dosia, Cook County, and Charleston. The Illinois River at Meredosia 
yielded three specimens, including the large one described, while the other 
localities yielded a single specimen each. It is a rare turtle over most of 
northern Illinois, and absent from the southern half of the state. 


Hapitat.—This species shows a considerable amount of variability 
as to its mode of life and habitat preference. Speaking in general terms, 
Emys blandingii is a semi-aquatic turtle: in certain regions it is largely 
a terrestrial species, while in others it is almost entirely aquatic in its 
habits. Thus in the region south of the tip of Lake Michigan the indi- 
viduals of this species tend to spend a great amount of time out of 
water, wandering about in the fields, woods, and sandy areas quite far 
from water. In the region about Meredosia on the Illinois River, indi- 
viduals are not ordinarily found far from the water, the turtles spending 
most of their time in the river itself or in either the tributary streams or 
adjacent swampy areas. Thus Garman (1892) says that it is oftener 
found in water than on land, but that it is essentially a terrestrial species 
—a rather curious mixture of ideas. The original habitat seems to have 
been the wet prairie regions of the state, but the draining of the soil and 
the cultivation of the fields have so altered the pristine conditions that 
the turtle has become extinct over most of what was originally its primary 
range. This would account in a measure, then, for the diverse habitat 
selections we find today, some individuals of an original swamp species 
attempting to adapt themselves to the dry land conditions they find, others 
taking to a more aquatic existence where large rivers and an abundance 
of water afford such an environment. 

Hapits.—There is probably no turtle found in Illinois whose habits 
and life history are less known than are these phases of the life cycle of 
Emys blandingu. Apparently not a common species anywhere, it has 
been largely neglected. Yet there has been a considerable amount of 
work done on the only other species of this genus, Emys orbicularis of 
southern and eastern Europe and southwestern Asia and northern Africa. 


THE TURTLES OF ILLINOIS—CAHN 81 


Incidentally, this curious distribution of two such closely related turtles 
(Emys orbicularis formerly ranged over Germany, Holland, Denmark, 
and the British Isles) is explained on the theory of old “land bridges” 
said by geologists to have existed during the Mesozoic and Cenozoic eras 
and as recently as the Pleistocene. Of especial interest in this distribu- 
tion are the postulated bridges between America and Europe across 
Greenland and Iceland on the east and the Asiatic bridge across what is 
now the Bering Strait on the west. 

Blanding’s turtle is very timid by nature. When frightened while 
sunning along the shore of the lake or upon a log in the pond, it plunges 
at once into the obscurity of the water and remains for hours hidden 
and withdrawn. Eventually it gathers enough courage to poke its eyes 
out of water, and then scrutinizes the surroundings with exceeding care 
before venturing upon further exposure. If surprised on land, it with- 
draws at once into its shell, which it closes as tightly as possible, and 
there it remains sealed and quiescent for a long time. If things remain 
quiet, the anterior lobe is slowly opened a crack so that the turtle can see 
out; if this experiment proves successful, the opening is increased and 
the head slowly, almost imperceptibly protrudes for a better view, and 
only after long deliberation will the turtle venture further. Morse (1904) 
makes the rather curious observation that once the turtle has withdrawn 
within its shell “no amount of thumping will cause it to open the hinged 
plastron” from which he assumes the very timid nature of the species. 
No amount of “thumping” will cause any turtle to forsake the protection 
which its shell affords. 

Though entirely at home on land, where the hinged plastron affords 
it efficient protection, Emys blandingii is an excellent swimmer, holding 
its own in all aquatic requirements with any of the species of pond 
turtles. Its underwater movements are fast and decisive; it swims with 
bold strokes that carry it forward with good speed. The bottom vegeta- 
tion offers it hiding facilities which it utilizes when disturbed, and it may 
on occasion be seen walking slowly about on the bottom in search of food. 
It can hold its breath with any of the pond turtles, and is capable of 
remaining under water fully as long as species of the genus Chrysemys. 
The variegated pattern and peculiar shading of the carapace blends well 
with the light and shadow of the vegetation. 

As to the hibernating period, there is also little information, due to 
the rarity of the turtles. Apparently they go into hibernation early, and 
come out rather late. The long period of inactivity is spent under water 
in many cases, and often in the mud at the bottom of the pond. Speci- 
mens have been taken at Meredosia from the underwater runways of 
the muskrat (Ondatra zibethica) and also from the mud of springfed 


82 ILLINOIS BIOLOGICAL MONOGRAPHS 


ditches. They are most often found while in hibernation by the probing 
method used to locate turtles during the winter, and the curious name 
of “glass turtle” arises from the peculiar glass-like sound caused by the 
steel point of the probe hitting the carapace of the turtle. 


NestinG Hasits.—In the literature, information on the nesting and 
breeding habits is confined to quotations from Agassiz as to the number 
of eggs laid, and very little else besides. Gadow (1901), however, has 
some interesting notes on the very closely allied Emys orbicularis which, 
since the species are very closely similar besides being the only two repre- 
sentatives of the genus in the world, may, perhaps, be of some interest, 
though whether they are relevant or not must be left to the future to 
determine. 

During the pairing season, on warm spring nights, they emit short piping 
sounds, and when they have found each other, the couple swim about together. 
The white, hard-shelled, long, oval eggs, averaging 25 to 15 mm, and about ten in 
number, are laid on land. This is a very laborious and curious business. The 
female having selected a suitable spot, not loose sand, but rather hard soil free 
from grass and other dense vegetation, prepares the ground by moistening it from 
the bladder, and the anal water-sacs. Then it stiffens the tail and bores a hole with 
it, moving the tail but not the body. The hind limbs then scoop out the hole, the 
broad feet moving alternately and heaping up the soil on the side, until the hole 
is about five inches deep, that is as far as the hind legs will reach. The eggs are 
laid at the bottom in one layer, divided and distributed by the feet. Lastly, the 
soil is put in again and the tortoise, by repeatedly raising its body and falling 
down, stamps the soil firm and flat, roughens the surface a little with its claws, 
and leaves the nest to its fate. Nothing but an accident leads to its discovery. 
The young are hatched, according to locality and the kind of season, either in 
the same autumn or not until the next spring. 

Eccs.—The eggs number from 6 to 10, though the ovaries of a large 
female will be found to contain hundreds of eggs of various sizes, these, 
of course, being the supply for future years. The eggs when laid are 
covered by a tough, white, unglazed shell. The average size of eight 
eggs which composed the complement removed from the oviduct of a 
large female just about to lay is 36.6 mm by 25.2 mm. The largest egg 
was 38 mm by 26 mm. 

IncupaTion.—If Emys blandingii resembles Emvys orbicularis, it is 
altogether possible that the eggs do not hatch until the spring following 
their deposition, passing the winter with a retarded metabolic rate so far 
as the embryo is concerned. Agassiz has hinted in several cases that this 
may occur, and experimentation and investigation of this phase of testu- 
dinate. development would be of great interest. 

Foop Hasits.—Unlike other species of pond turtles, Blanding’s turtle 
apparently feeds readily both on land and in the water. On land it eats 
grasses, leaves, berries, and other succulent vegetation with relish, and 


THE TURTLES OF ILLINOIS—CAHN 83 


has no difficulty in swallowing this food in the absence of water. Insect 
larvae, grubs, slugs, and earthworms vary the vegetable diet on land, the 
animal matter composing about 30 per cent of the contents of the only 
“terrestrial” stomach available to the writer for study. In their water 
environment they feed with equal avidity upon frogs, tadpoles, crayfish, 
minnows, and the larger larvae of aquatic insects. It speaks well for the 
speed of this turtle to note that it catches these active forms with appar- 
ent ease and surety. Also it is interesting to note that this species is able 
to swallow food both under water and while on land. 


TABLE 7.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Emys Blandingit 
(Measurements in millimeters) 


z Carapace Plastron 
locas Head Tail Sex 
: Length | Width | Length | Width | Depth | 
De Seer 240 164 220 116 83 38 103 | ie} 
Dine a saa 172 122 170 98 63 28 65 | .. 
Sree: 64 50 50 40 26 13 | 25 | 
i 


Economic ImportaNce.—This turtle is far too rare to have any 
economic value to man, but there is an abundance of good meat on it, 
which is both palatable and of excellent flavor. It is never a scavenger 
by habit, and its innocuous food habits certainly cannot be damaging 
to man. 

PaRAsITES.—Though I have examined only three Illinois specimens, 
I have failed to find any trace of either trematode or nematode parasites, 
nor any evidence that the species is seriously attacked by leeches. 


GENUS TERRAPENE MERREM 


Terrapene (part) Merrem 1820 
Cistuda (part) Flemming 1822 
Cistudo Bonaparte 1830 

Emys (part) Wagler 1830 
Diclida (part) Rafinesque 1832 


Emyoides Gray 1844 

Onychotria Gray 1849 

Pariemys Cope 1895 

Toxaspis Cope 1895 

Didicla Fowler 1906 ( = Diclida Raf.) 


Pyxidemys (part) Fitzinger 1835 


Shell high, globular, convex. Plastron large, completely filling the 
aperture, rounded anteriorly and posteriorly, and united to the carapace 
by a ligament and movable upon it. Plastron divided into two movable 
lobes by a transverse hinge between the pectoral and abdominal elements; 
axillary and inguinal scutes rudimentary. Humero-pectoral suture meet- 
ing the entoplastron at about its middle. Dorsal surface of the head 
covered by smooth skin only. Alveolar surface of the jaws narrow and 


84 ILLINOIS BIOLOGICA L MONOGRAPHS 


without a median ridge; upper jaw with beak projecting downward. 
Choana between the eyes large; no bony temporal arch present. Digits 
with but a slight web or none. Tail very short. 


Terrapene carolina carolina (Linnaeus) 


(Common box turtle; sand turtle) 


Testudo carolina Linnaeus 1758 
Testudo carinata Linnaeus 1758 
Testudo brevi-cauda Lacépéde 1788 
Testudo clausa Gmelin 1788 

Testudo incarcerata Bonnaterre 1789 


Testudo incarcerata-striata Bonnaterre 


1789 
Testudo virgulata Daudin 1802 
Emys clausa Schweigger 1812 
Emys virgulata Schweigger 1812 
Emys schneideri Schweigger 1812 
Cistudo clausa Say 1825 


Terrapene maculata Bell 1825 
Terrapene nebulosa Bell 1825 
Terrapene virgulata Fitzinger 1825 
Emys carolina Gray 1831 

Cistudo carolina Gray 1831 
Pyxidemys schneideri Fitzinger 1835 
Pyxidemys virgulata Fitzinger 1835 
Pyxidemys clausa Fitzinger 1835 
Cistudo virginea Agassiz 1857 
Terrapene carinata Strauch 1862 
Cistudo clausa clausa Cope 1875 
Cistudo carinata S, Garman 1884 


Cistudo carolina carolina H. Garman 1892 
Didicla ( = Diclida) carolina Fowler 1906 


Terrapene clausa Merrem 1820 
Terrapene carolina Bell 1825 


Description.—The range of variations of shape, markings, and color ~ 
of Terrapene carolina carolina is almost unlimited, so that any two 
specimens are hardly more than similar even though they have come 
from the same locality. So infinite are these variations that I can do 
no better than to describe a typical specimen and indicate the range of 
various characters. The shell is usually oval, somewhat narrower toward 
the anterior end than toward the posterior, but in some cases the in- 
dividuals are nearly round. Carapace highly convex, arched, globular, 
the marginals entire over the anterior two-thirds of the carapace, but 
tending to become serrate in the posterior third, with a conspicuous 
though small caudal notch. Vertebral scutes of moderate size. The first 
vertebral is pentagonal, the two anterior margins tending to unite medi- 
ally in a point which intrudes into the posterior margins of the first 
paired marginals. Second and third vertebrals hexagonal, the anterior 
and posterior margins almost equal and longer than those of the re- 
maining four sides which are approximately equal. The fourth vertebral 
tends to be heptagonal in some specimens, hexagonal in others, the varia- 
tion occurring in the anterior margin. Fifth vertebral, the smallest of 
the series, roughly hexagonal and wider than long. There is a distinct, 
though low and blunt, vertebral keel, most conspicuous on the second, 
third, and fourth scutes. The anterior three costals are large. The first 
is trapezial in shape, the dorsal (median) margin being the shortest. 
Second costal the largest of the series, rectangular. Third costal roughly 
rectangular and somewhat smaller than the second. Fourth costal by 


on 


THE TURTLES OF ILLINOIS—CAHN 8 


far the smallest of the series and about the size of the fifth vertebral, 
tending toward square. Nuchal small or (rarely) absent. Anterior and 
posterior marginals flaring, the posterior more so than the anterior, 
though the caudals are nearly vertical; edge entire up to about the eighth 
scute where serration usually begins. There are twelve paired marginals. 
All scutes of the carapace with finely etched concentric lines. The focus 
of these lines lies at the posterior median border of the vertebral scutes, 
in the center of the dorsal third of the costals, and at the posterior- 
lateral angle of the marginals. Plastron large, completely closing the 
aperture. It is divided into two lobes by a ligamentous hinge between 
the pectoral and abdominal scutes, both lobes being movable. It is at- 
tached to the carapace by a ligamentous hinge in lieu of any trace of a 
bridge. Gulars large, triangular. Humerals a truncate triangle, the in- 
terhumeral suture being short. Pectorals rectangular and approximately 
twice as wide as long. Abdominals also rectangular, larger than the 
pectorals. Femorals very large, triangular, the interfemoral suture being 
the shortest of the ventral sutures, and the plastron is widest across the 
femorals. Anals very large, triangular, the interanal suture the longest 
of the ventral median contacts, and without an interanal notch. There is 
a tendency to show concentric striae on the plastral elements, but these 
are usually nearly worn off; the focus of these is at the posterior lateral 
angle of the scutes. The mid-ventral suture tends to be a straight line, 
with few undulations. Axillary and inguinal elements usually absent, 
or at best very rudimentary. Head of medium size, covered with a 
smooth, tightly drawn skin. Upper 
jaw hooked, entire, without a notch 
at the symphysis; lower jaw with 
an upward hook. Alveolar surfaces 
narrow and without a median keel 
or ridge. Limbs and feet strong, 
scaly ; digits with very rudimentary 
web, or free. Claws of the fore feet 
TEXT-FIGURE 11—The skull of Ter- short, but strong and five in num- 
rapene carolina carolina. Q—quadrate. ber: four claws on the hind feet, 
longer than those on the fore. Tail 
short and stubby. Of osteological characters, Taylor (1895) points out 
that the zygomatic arch is absent; the quadrato-jugal is rudimentary and 
triangular, articulating only with the quadrate; post-orbital arch wide, 
the jugal being relatively wide and short; phalanges: fore limb 2-3-3-3-2 
or 2-3-3-2-2; hind limb; 2-3-3-3-2. 
CoLoraTIon.—Extremely variable. The carapace is dark brown or 
nearly black, with blotches, stripes, and hieroglyphics of yellow or 
orange. Sometimes the yellow predominates, sometimes the dark brown 


86 ILLINOIS BIOLOGICAL MONOGRAPHS 


Pirate 11.—Terrapene carolina carolina: A, Adult male, ventral view. 
B, Same individual, dorsal view. C, Newly hatched young, ventral view. D, Newly 
hatched young, dorsal view. E, Head study of an adult. F, Adult, lateral view. 


THE TURTLES OF ILLINOIS—CAHN 87 


ground color. While the yellow markings are extremely irregular, the 
tendency or plan is for them to radiate from the center of the growth 
point of the scute. The vertebral keel is marked by either a yellow 
line or a series of elongated yellow blotches. The plastron varies from 
clear yellow to clear ebony black or mahogany brown, with every con- 
ceivable variation between. Sometimes the colors are demarked into 
distinct areas of solid color; sometimes the entire plastron is intricately 
mottled. Soft parts brown, sparsely or heavily marked with round spots 
of yellow or orange, particularly about the neck and fore limbs. Jaws 
yellow, with black spots or lines. Iris varies from brown to bright 
scarlet. 

Younc.—The young are much more round than the adults and the 
vertebral keel is far more distinct and considerably higher in proportion. 
Each vertebral scute tends to have a yellow spot on the portion of the 
keel associated with it, and there is a similar yellow spot on each costal, 
while the marginals usually have a yellow mark (not a round spot) at 
their lateral margins. I have one young turtle of this species which does 
not have a trace of the usual spots on the carapace. The color of the 
carapace is, otherwise, uniformly brown. Plastron yellow, with a large 
central area of dark brown occupying most of it. The tail is relatively 
larger in the very young than in the adults. 


TEXT-FIGURE 12.—Sex differentiation in Terrapene carolina 
carolina. (Above) Ventral views of the tail and of the right 
hind foot, male and female. (Below) Diagrammatic longi- 
tudinal sections through the plastron, male and female. 4— 
anterior; H—hinge; P—posterior. 


88 ILLINOIS BIOLOGICAL MONOGRAPHS 


Sex DIFFERENTIATION.—There are a number of secondary characters 
which are associated with the sex of the individual, and these may be 
listed as follows: (1) The tail of the male is longer than that of the 
female, the difference lying in the distance of the anus from the plastron, 
not in the distance from the anus to the tip. (2) Hence the anal aperture 
opens beyond the carapace in the male, and below the carapace in the 
female. (3) The claws of the hind foot of the male are short and 
stocky and considerably curved; in the female the claws are longer, 
more slender and less curved. (4) Plastron of the male is concave in 
the anterior region of the hind lobe just posterior to the hinge; no such 
concavity exists in the female. (See Text-fig. 12 for diagrams represent- 
ing longitudinal cross sections through the plastron.) (5) The carapace 
of the male tends to have a greater flare at its posterior corners than is 
the case in the female. (6) The nuchal notch is more marked in the male 
than in the female. (7) Relative height and width of the male is greater 
than of the female. (8) The iris of the male tends to be red or pink; of 
the female yellow or brown. (This is generally but not always true). 


GroGrRapHic DistripuTION.—The range of Terrapene carolina caro- 
lina includes the major portion of northeastern United States, extending 
as far north as the Great Lakes and the St. Lawrence River. It occurs 
over most of New England, including the coastal states of Maine, Massa- 
chusetts, and New Jersey, and extending southward to Georgia. The 
western limit of its range lies in Wisconsin, Illinois, and Missouri. In 
Pennsylvania (Surface, 1908) it is found to be statewide, excepting for 
the pine barrens country, where it is absent. Morse (1904) reports that, 
while nowhere abundant in Ohio, it is to be found over the entire state, 
and Hay (1892) reports a similar distribution for Indiana. Ruthven 
et al (1912) report it from several southern counties in southern Michi- 
gan. Blanchard (1922) reports it from western Tennessee, while Hurter 
(1911) reports but a single specimen taken from the west side of the 
Mississippi, in Missouri. In the northwestern portion of its range it 
is reported from southern Wisconsin as far north as Green Bay by Pope 
and Dickinson (1928), although Higley (1889) fails to mention it for 
that state, while Cahn (1929) adds one record for southern Wisconsin. 
There is no ground for the statement by Pope and Dickinson that it 
is probably “statewide” in its distribution in Wisconsin. 

Ittrnors Recorps.—Within the state of Illinois there are records 
of the box turtle, Terrapene carolina carolina, from numerous localities. 
Yarrow (1882) reports specimens from Mt. Carmel (9512) and Fairfield 
(9939) in the U.S. National Museum. Garman (1892) records it rrom 
Duquoin, Eldorado, Cobden, Anna, Fairfield, and Mt. Carmel. Hurter 
(1911) found it in Madison, Monroe, St. Clair, Randolph and Union 


THE TURTLES OF ILLINOIS—CAHN 89 


counties in the Mississippi River region; Hankinson (1915, 1917) reports 
it from the Charleston region, Blanchard (1924) in Johnson and Monroe 
counties, and Shenck (1886) has some interesting notes from Albion. 
The Field Museum has a specimen from Olive Branch (2219). Gaige 
(1914) reports T. carolina from Richland county, but in a personal 
letter this is corrected, the specimen proving to be Terrapene ornata. The 
present writer has examined speci- 
mens from the following localities: 
Centralia, Robinson, Toledo, Anna, 
Cobden, Mt. Carmel, DuQuoin, 
Alto Pass, Litchfield, Norris City, 
Urbana, Carmi, Benton, Marion, 
Charleston, and Carbondale. 


Hasitat.—The common box 
turtle is distinctly and preémi- 
nently a woods species, essentially 
terrestrial in its habits, yet, as we 
shall see later, with certain aquatic 
or semi-aquatic inclinations. Its 
favorite haunt is in dry deciduous 
woods with plenty of underbrush 
and herbaceous ground cover. 
Here the turtles wander in search 
of food by day and seek shelter 
under the protection of the brush 
at night. Again, the turtles wander 
out into the grassy fields or into 
areas under cultivation. Hillsides 
afford a congenial environment, 
especially those with a southern 
exposure, where the early spring 
sun limbers them up after 
hibernation. 


Map 8.—Terrapene carolina carolina. 


Hasits.—Because of the very gentle nature possessed by these turtles 
and the ease with which they adapt themselves to confinement they have 
been much studied and watched, and there is a considerable literature on 
their general behavior. The box turtle is of a very timid disposition. If 
discovered, it freezes in whatever position it happens to be, and awaits 
further developments without a movement. If the danger approaches, it 
withdraws its head within the shell with a hissing sound caused by the 
expulsion of the air from the lungs necessary to accommodate the in- 
clusion of the head and neck within the limited space available. The legs 


90 ILLINOIS BIOLOGICAL MONOGRAPHS 


are drawn in, after which the front and hind lobe of the plastron are 
closed tightly, and the turtle is impregnable. So tightly do the lobes close 
the aperture that it is impossible to insert a knife blade into the crack if 
one would pry a lobe free: one is far more likely to break the blade than 
to succeed in opening the shell. Again, if the turtle is teased too much, 
it is likely to resort tor a time to snapping and feeble lunges, especially 
during the breeding season when the males seem to develop somewhat of 
a temper. Under “domestication,” however, both the temper and the 
timidity are quickly overcome, and the turtle soon learns to eat eagerly 
from the hand that offers food. 

Hibernation begins with the cooler weather of late October. At first 
the turtles dig in at night only and come out during the warmer portions 
of the day, but as the days grow cooler the turtles remain longer and 
longer in their holes until they fail to appear at all during the daytime. 
At first they do not bury themselves to a depth of more than a few inches. 
As the weather grows colder they work themselves further and further 
into the ground until they have gone down from a foot to eighteen inches 
or even to a depth of two feet. The following tabulation shows the 
progressive depths of hibernation as found by the writer by probing 
down to a turtle known to be hibernating: 


Date Depth Date Depth 
(in inches) (in inches) 
October” 2Zlaees snake nee oeee 2 November 255 e7 uae seuam ee seer 16 
@ctoher 28sec eerctee cee 5 November o0t.es. ee eee cee 19 
November 4 as tsisencam ese ncee 5 December 5 twas aes eee eee 19 
November 11.24 1.3. 4ceenanene 9 Rebruary: Orn aaccus sees aie se 19 
November l8tee ce eeeie see cere 11 


If taken out of hibernation the turtle is to all appearances dead, but in 
the proximity of heat it slowly revives and in a few hours is looking 
around inquisitively. The species comes out of hibernation in April, the 
exact time depending largely upon the weather. If a late cold spell de- 
scends upon the turtles after they are out, many die of exposure: appar- 
ently their adjustment to the environment is a rather slow process. 

A great deal has been written both about the avoiding of water by 
the box turtle and about the aquatic habits of the species. The belief is 
firmly fixed in the popular and scientific mind that the box turtle avoids 
water, and the appearance of many brief notes, many written apparently 
in a spirit of astonishment, calling attention to a turtle found somewhere 
associated with water have failed to make much of an impression. The 
significance of these notes, namely, that Terrapene carolina carolina has 
a distinct use for and attraction to water has not yet filtered through the 
consciousness of the writers. Yet such is the case. During the hot 


THE TURTLES OF ILLINOIS—CAHN 91 


periods of the summer we find the box turtle going into a state of 
aestivation closely akin to its period of hibernation, during which it re- 
mains quiescent, buried in the ground. Often this aestivation is passed 
buried in mud, as noted by Hurter (1911), Overton (1916), Engelhardt 
(1916), and others. The site is usually a mudhole, and in the wet mud, 
buried to a depth of from two inches to nearly a foot, the turtles spend 
the periods of excessive heat. If the space is limited, the turtles pile up 
on top of each other, and Hurter reports six taken from a space three 
feet in diameter. Latham (1916) reports a regular procession of box 
turtles heading toward a small mudhole in August, with sixty to seventy 
individuals already gathered in and about the puddle. 

A still more (apparently) unusual use of water by the box turtle 
came under my observation during the fall of 1931 and the winter fol- 
lowing. In the spring of that year I liberated some 24 adult specimens of 
Terrapene carolina carolina and 17 of T. ornata representing both sexes 
in an outdoor pen measuring 40 by 12 feet. At one end a pipe poured a 
steady stream of water, forming a puddle six inches deep and about a 
yard in extent. In late October all of the 7. ornata went into hibernation 
and were seen no more until spring. It was a very mild fall, and T. caro- 
lina carolina did not begin to think about hibernation until November 2, 
and soon afterward all went into the ground except five specimens, which 
about this time took up their abode in the water and were apparently 
quite contented in the puddle. The interesting part is that these re- 
mained in the water the entire winter, occasionally poking their noses 
out for air on the milder days, but remaining almost immobile during 
the three months of winter. On a particularly mild day in January one 
specimen came out on the land, and went in again in the afternoon; the 
air temperature of this day was 11° C. Two days later (January 29), 
one went for a walk and got too far from the water; it was found frozen 
to death the next day. The following data in regard to one of these 
water-hibernating turtles are of interest: air temperature, 3° C; water 
temperature, 10° C; body (rectal) temperature, 9.5° C. Subsequent 
readings showed that the body temperature remains about 1° C below 
that of the surrounding water. 

The box turtle is capable of swimming and is, in fact, quite good at 
it, though because of the globular form of its shell and the shortness of its 
legs, swimming is an awkward and laborious process. It swims at the 
surface, with the dome of the carapace and the head out of water, and I 
have never seen one swim below the surface; in fact, they seem to be too 
buoyant to get under. The turtle paddles slowly along, resting repeatedly 
as it floats at the surface, to continue its progress toward shore at broken 
intervals. The young seem to be more aquatic than the adults. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


92 


ayeur dy} ‘JJo] oY} UO ST aeWdy dy, ‘UOT}e[NdOD UT sayjin} xog 


‘JYySII 9y} uO 
IDUYOADI DUYOADI IUadDAAI[—Z] ALVIg 


Ra 


LA 


Poiana ieee aa 


THE TURTLES OF ILLINOIS—CAHN 93 


This turtle leads a rather uneventful, quiet sort of life. During the 
day the creatures wander about rather aimlessly in search of food. When 
night comes they sometimes dig into the ground and conceal themselves ; 
with morning they dig out again, working forward, not backing out of 
the hole by which they entered their retreat. As they eat they grow fat, 
and specimens taken in the late fall prior to hibernation are likely to be 
so fat that they are unable to withdraw completely within the shell. They 
are comical at such times. If pressure be applied at one end of the shell 
the turtle pops out at the other end as it attempts to withdraw the end 
that is in danger within the protection of the shell, a procedure which its 
corpulent condition renders impossible. 

There are a number of interesting notes scattered through the litera- 
ture which throw some light on the longevity of this species. Thus Dr. 
Shenck (1886) records an item of interest from Albion, [linois. A 
turtle with initials engraved upon its carapace in 1824 was recaptured in 
1865, marked with an additional initial and again liberated. It was re- 
captured again in 1885 within half a mile of the original spot of its 
capture, still bearing clearly all of the initials. Hence this turtle was 61 
years old at least, but to this must be added the fact that it was already 
fully grown when the initials were first put on in 1824. Initials carved 
on turtles ordinarily cannot be taken too seriously as proving anything, 
but this case seems to be authentic. It emphasizes further the fact that 
the range of the individual box turtle is very limited and that the adults 
at least are not prone to wander far from “home.” Not only are they 
long-lived, but the fact that they may survive under difficult conditions 
is indicated by turtles which Dr. R. W. Shufelt kept alive, without either 
food or water, for an entire year. 


Nestinc Hapits.—Copulation takes place very shortly after the 
animals emerge from hibernation, the male mounting the female for a 
considerable period of time, after having subdued her by a rather vicious 
attack during which the beak and front feet are effectively used. The 
act of copulation has been described by Cahn and Conder (1932). The 
pair described was found in copulation, the male standing nearly erect 
upon the posterior end of his carapace, his legs pressed firmly into the 
inguinal area of the female, being assisted in this by the female which, 
her legs outside those of the male, pressed his legs yet more firmly in 
place. This represents a sort of “posterior amplexus.’’ How long the 
pair had been thus in contact is unknown, but they remained thus for an 
hour and three-quarters, during which time they were handled frequently 
and photographed. This report is confirmed by Ewing (1933). 

Prior to the act the male may follow a given female for days. After 
copulation the male remains as if exhausted, immobile for several hours, 
while upon the female the process seems to have no effect whatever. 


94 ILLINOIS BIOLOGICAL MONOGRAPHS 


The nest is made usually in sand, but eggs have been found deposited 
in the rich agricultural soil of cultivated fields. The nest is dug entirely 
with the hind legs, and requires several hours for completion, for the 
work is done leisurely. It is between three and four inches wide and ex- 
tends into the ground a distance of three or four inches. The female 
backs into the hole as she digs and continues until she is nearly below 
the surface of the ground. In this excavation she deposits from three 
to eight eggs, five to seven being the average number. Each egg is 
worked into its proper position after it is laid, and by manipulation 
with the hind feet, each is buried separately. It takes about three- 
quarters of an hour to complete the laying of the.eggs. When the last 
egg is concealed, the turtle fills up what remains of the hole, smoothing 
the surface and eradicating all signs of the nest by dragging the plastron 
over the ground several times. The period of incubation is about three 
months. Females of the species, liberated in my outdoor pen in early 
June (at which time dissection of certain ones showed hard-shelled eggs 
in the oviduct), had the young hatch on October 8. However, this pen 
was shaded by buildings and by vegetation, and received but little direct 
sunlight, which may perhaps have lengthened the period of incubation. 

It is a well-known fact that, in spite of the abundance of Terrapene 
carolina carolina in certain regions, the newly hatched or partially grown 
young are but rarely found in nature. The young which hatched in my 
pen headed immediately toward the puddle of water at one end, entered 
it and remained hidden in the vegetation and beneath the bottom débris 
until I fished them out before the cold weather set in. In the laboratory 
they immediately burrowed under the sphagnum which covered the 
ground in their little enclosure, and remained embedded in the moist earth 


TEXT-FIGURE 13.—Posterior ends of the shells of a pair of 
Terrapene carolina carolina in copulation; ventral view of 
plastron of female; dorsal view of carapace of male. 


THE TURTLES OF ILLINOIS—CAHN 95 


for weeks at a time. These facts may well give a clue to the reason for 
the scarcity of small box turtles. The very young possess a terminal egg 
tooth which they use in picking their way out of the egg; it is lost within 
a week after hatching. 

Eccs.—The eggs number, as we have said, between three and eight in 
a clutch. They are oval in shape, the curvature of the ends being equal. 
The shell membrane is very thin and flexible, the eggs having a soft, 
pliable feel when handled. The average size of a typical egg is 33.17 mm 
by 19.5 mm, this figure obtained by measuring 54 eggs of the species. 
The largest egg in the series examined measured 35 mm by 19 mm; the 
smallest 30.5 mm by 18.5 mm. Ewing (1933) offers interesting data on 
the subject of the eggs and incubation period, and shows that for Wash- 
ington, D. C., “the earliest date of egg laying was June 22; the latest 
date was July 14. The average date for egg laying was July 1. The 
average date for the emergence of the first young individual of a nest 
was September 26. The average number of eggs laid at any one time by 
a female was 3. The percentage of eggs found to be fertile was 78.6.” 
In a table he shows the incubation period to vary from over 69 days to 
over 103 days, and from his data one obtains the average incubation 
period as 88 days. 

Foop Hasirs.—The diet of Terrapene carolina carolina is a mixture 
of both vegetable and animal matter, with the former predominating in 
most cases. The vegetable material consists of a great variety of plants, 
including the roots, stems, and leaves of a host of species of flowering 
plants, berries, fruits, and some seeds. Fungi are particularly liked ac- 
cording to a number of authorities, though I have never found evidence 
of this in specimens examined from Illinois. The animal matter con- 
sumed includes earthworms, snails, slugs, myriapods, and a great variety 
of insect species, coleopterous forms ordinarily predominating. Reports 
mention the fact that the box turtle is fond of lettuce and of cucumbers 
and muskmelons and that they sometimes damage these crops; this dam- 
age cannot, however, really amount to much. In captivity the young 
feed well upon bananas, lettuce, apples, and various succulent fruits, but 
if not permitted to hibernate they cease eating entirely, no matter what 
enticing morsels are offered them, and death usually follows before the 
winter is over. 

Economic Importance.—The insect-eating proclivities of this species 
make it a highly desirable turtle to have around, for the diet includes 
many species of noxious insects—such as cutworms, grasshoppers, cater- 
pillars of various species, ants, flies and their larvae, and several species 
of injurious beetles. Though usually edible, the box turtle is ordinarily 
not used for food. Babcock (1919) reports an instance in Pennsylvania 


96 ILLINOIS BIOLOGICAL MONOGRAPHS 


where, during a coal strike, the miners went afield and gathered in box 
turtles which they ate, and which promptly made them ill. It is assumed 
that they had fed upon some species of poisonous “toadstool” which 
rendered the turtles temporarily poisonous, but which did not poison 
them. This is a more than likely supposition, for the box turtle is par- 
ticularly fond of fungi of various sorts. It is not at all a scavenger and 
only rarely or under peculiarly adverse circumstances preys upon other 
vertebrates of any sort. 


Parasites.—Being a terrestrial form, the box turtle is not subjected 
to attacks of leeches, and intestinal worms are not overly common. I have 
on two occasions dissected out the large white larvae of a species of bot- 
fly imbedded in the neck region. These occupied a cavity nearly half an 
inch deep, yet seemed to cause the turtle but little inconvenience. 


TABLE 8.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Terrapene carolina carolina 
(Measurements in millimeters; weight in grams) 


Carapace Plastron Tail 
=pedmen Head Weight | Sex 
Length| Width | Length} Width | Depth Total A-T 
seer eee 134 | 105 | 128 75 62 22 36 20 371 a 
Dota oe sea Gers 94 84 93 65 48 16 26 20 169 9 
Bee Sef are t 138 | 108 | 142 90 75 22 27 24 550 9 
A aaa ace 137 | 101 | 135 75 70 22 27 25 536 9 
Sh ete Peat 122 96 | 118 76 69 20 22 18 317 Q 
Chee ae er 141 111 139 86 73 22 20 15 584 9 
To Sa soiirr Sao 141 112 | 130 80 60 23 35 18 424 ey 
Shee ae | 99 79 96 61 50 17 25 20 166 |Im. 9 
Dnetartthaa etinale 89 70 84 57 41 18 116 [Ima 
LOewccneia acd 139 | 113 | 132 82 65 23 30 14 452 ey 
Liye ee 141 112 | 137 79 60 24 31 14 416 a 
12oSeat eee 125 92 | 121 77 55 20 35 20 294 a 
1S Rear comin 50 46 48 37 22 10 18 15 27 |Im. a 
14 eae, ssc 81 65 80 51 38 15 16 14 106 |Im.o" 
1 See eee ee 151 116 | 141 87 68 21 38 31 620 9 
NGM se oeciie Ske 145 | 110 | 135 81 66 22 40 18 475 a 
17h ee gr 140 | 110 | 133 82 71 22 36 33 496 2 
AB nasties anit 60 56 57 41 27 12 16 14 31 |Im. 9 
Terrapene ornata (Agassiz) 
(Painted box turtle; sand turtle) 
Cistudo ornata Agassiz 1857 Terrapene ornata cimarronensis Cragin 1894 


Terrapene ornata Baur 1891 


Description.—Shell broadly oval, the width equalling approximately 
three quarters of the length. Carapace high, but much flattened dorsally ; 
anterior slope gradual, posterior (caudal) slope abrupt. First vertebral 
scute pentagonal, the anterior margins meeting in a median point which 
projects far into the nuchal. Second, third, and fourth vertebrals hex- 
agonal, the width exceeding the length. Fifth vertebral pentagonal, and 
placed nearly vertically; it is the smallest of the series. There is no 


THE TURTLES OF ILLINOIS—CAHN 97 


trace of a vertebral keel. Costal scutes large, wider than long. The first 
costal trapezial, the median dorsal margin the shortest. Second and third 
costals roughly rectangular, approximately twice as wide as they are 
long. Fourth costal trapezial, and the smallest of the costal series. 
Nuchal small, forked posteriorly, the tip of the first vertebral fitting into 
the V-shaped notch. Anterior and posterior-lateral marginals flaring, the 
mid-lateral and caudal marginals vertical and without a flare; no inter- 
caudal notch. Plastron large, but not quite filling the aperture. It is 
divided into an anterior and posterior lobe by a ligamentous hinge 
between the pectoral and abdominal scutes, both lobes being movable. 
The plastron is widest across the abdominal scutes. Gulars acutely tri- 
angular. Humerals approaching triangular, with a short interhumeral 
suture which is usually (though not always) the shortest of the mid- 
ventral sutures. Pectorals rectangular, the interpectoral suture usually 
exceeding the interhumeral suture, 
though this is not always the case. 
Abdominals rectangular. Femorals 
trapezial, the interfemoral margin 
the shortest of the sides. Anals 
large, the largest of the plastral 
elements, triangular ; their posterior 
margin is even, straight; and there 


is no inter-anal notch. The longitu- = TExt-Ficure 14.—Skull of Terrapene 
dinallnid ventral’ cut dries ornata (for comparison with Text-fig. 
id-ventral suture undulates 11). 


considerably as small portions of 

the right and left plastral elements tend to intermesh. The plastron is 
attached to the carapace by a bridge formed by a very short wing of the 
abdominals ; it is inconspicuous, but distinct. Axillary element large and 
conspicuous; inguinal either rudimentary or absent. Oiten the scutes of 
the carapace show concentric striae about the growth point of each scale ; 
these are more marked on the costals and marginals than on the verte- 
brals. Similar striae sometimes are in evidence upon the plastral scutes, 
but usually these are worn off, leaving the plastron smooth. Head rather 
small, scaly, the dorsal surface covered by a tightly drawn skin. Upper 
jaw strongly hooked, and with a distinct median notch. Limbs strongly 
scaled, the scales larger and more prominent on the front limbs. Digits 
of front limb five, each with a strong, straight claw; digits of hind limb 
also five (though the fifth is exceedingly rudimentary), the four larger 
with slender, somewhat curved claws, the innermost being very small and 
weak. All digits without distinct webbing. Tail short, slender. Oste- 
ological features: zygomatic arch entirely absent ; quadrato-jugal absent; 
postorbital arch very slender. Phalanges in fore limb 2-2-2-2-2; in hind 
limb 2-3-3-3-1. 


98 ILLINOIS BIOLOGICAL MONOGRAPHS 


CoLorATion.—Terrapene ornata does not show nearly as much varia- 
tion in either color or pattern as does T. carolina carolina. The carapace 
is usually a chocolate brown, with local tendencies toward a reddish 
brown. Each scute of the vertebral and costal series is marked with 
dashes and lines of bright yellow, which tend to radiate from the growth 
center. There is a tendency to form a mid-vertebral yellow line, but this 
is ordinarily somewhat broken up into a series of long yellow dashes. 
The lateral portion of the marginals bears a yellow patch of irregular 
shape and of variable size. The plastron is yellow, highly and con- 
spicuously mottled in an elaborate, asymmetrical design of red-brown. 
Head and neck dark brown, spotted with pale yellow, especially on the 


PLATE 13.—Terrapene ornata: A, Adult, ventral view. B, Adult, dorsal view. 
C, Adult, lateral view. D, Immature individual, two and a quarter inches long. 


THE TURTLES OF ILLINOIS—CAHN 99 


top and sides. Each scale of the fore limbs bears a conspicuous yellow 
dot on a dark brown background. Tail with a pale yellow mid-dorsal line. 


Younc.—I have been entirely unable to locate a newly hatched speci- 
men of Terrapene ornata, and there is no description of the young in 
literature. Agassiz figures the young, but unfortunately in such a posi- 
tion as to make description of it impossible. It appears to have a light 
(yellow?) blotch on the costal scutes, and a mid-dorsal light (yellow?) 
vertebral stripe. The fact that the young are without a trace of a 
vertebral keel is mentioned by several authors. 


Sex DIFFERENTIATION.—The females have short tails, the males long 
tails, the difference lying in the fact that the anus of the male is beyond 
the carapace, while in the female it is located under the edge of the 
carapace; the difference in length lies between the anus and the tip: this 
distance is less in the female than in the male. Males have the claw on 
the first digit of the hind foot turned abruptly forward. The males can- 
not be distinguished, as can those of T. carolina carolina, by either the 
depression in the center of the plastron (which does not occur in T. 
ornata) or by the color of the iris of the eye. 


COMPARISON OF SPECIES OF TERRAPENE.—Many people seem to have 
considerable difficulty in distinguishing between the two species of box 
turtles, T. carolina carolina and T. ornata, found in Illinois. In an effort 
to point out the most marked differences, the following comparison is 
offered: 


1. Carapace of carolina is arched, or domed. 
Carapace of ornata is flattened on top, or depressed. 
2. Vertebral scutes of carolina with a median keel. 
Vertebral scutes of ornata without a keel. 
3. Plastron of carolina is widest across the femorals. 
Plastron of ornata is widest across the abdominals. 
4. Plastron of carolina without a bridge. 
Plastron of ornata with a short but distinct bridge. 
5. In carolina the axillary element is absent or rudimentary. 
In ornata the axillary element is well developed. 
6. Plastron of carolina completely closes the aperture. 
Plastron of ornata is a bit too short to close it completely. 
7. Upper jaw of carolina is not notched at the tip. 
Upper jaw of ornata is notched at the tip. 
8. In carolina the length of the plastron very rarely equals that of the carapace. 
In ornata the length of the plastron ordinarily exceeds that of the carapace. 
9. When fully grown, carolina is a considerably larger turtle than is ornata. 


Osteological differences: 
10. Postorbital arch of carolina is stout. 
Postorbital arch of ornata is very slender. 
11. Quadrato-jugal of carolina is present but rudimentary. 
Quadrato-jugal of ornata is absent. 


100 ILLINOIS BIOLOGICAL MONOGRAPHS 


GrocrapHic Distrinution.—According to Stejneger and Barbour 
(1923) the range of Terrapene ornata is: “Indiana, Ilinois and the terri- 
tory between the Missouri and Mississippi rivers and the Rocky Moun- 
tains from the Yellowstone River in the north to the Gulf of Mexico in 
the south, southern New Mexico, Arizona and northern Mexico.” In gen- 
eral terms, 7. ornata may be said to be a western form which reaches 
its eastern limit of distribution in eastern Illinois, while 7. carolina 
carolina is an eastern form which 
extends westward approximately 
to the Mississippi River. Ellis and 
Henderson (1913) report it from 
Colorado; it is reported by various 
authors from Wyoming, Kansas, 
Oklahoma, Nebraska, Arkansas, 
New Mexico, and Texas. In the 
southern United States it does not 
occur east of Texas. Hurter 
(1911) reports it generally dis- 
tributed over Missouri. Hay does 
not list it in either of his reports 
on Indiana. Evermann and Clark 
(1930), however, report 7. ornata 
as established in the Lake Maxin- 
kuckee region of northern Indi- 
ana since about 1923. For Wis- 
consin, Higley (1889) records it 
from Walworth County, while 
Hoy (1883) reports it from Grant 
County; Pope and Dickinson 
(1928) add a specimen from Co- 
lumbia County, and give its range 
in the state as “apparently only 
southern Wisconsin.” Blanchard 
(1922 reports it as very rare in Map 9.—Terrapene ornata. 
Dickinson County, Iowa. 


Itt1nots Recorps.—There are relatively few records for Illinois for 
this species of box turtle. Garman (1892) records it only from Fairfield, 
as does Hay (1892); as a matter of fact, both of these reports are the 
Yarrow (1882) record, U. S. National Museum #9937, 9938, 9940. 
Hurter (1911) reports it from Baldwin, Randolph County, and from 
Addieville, Washington County. Taylor (1895) had a specimen from 
Kankakee, and another specimen (U. S. National Museum 7542) sent 
in by Kennicott from “Illinois.” Vestal (1913) found it in Mason 


THE TURTLES OF ILLINOIS—CAHN 101 


County, and Blanchard (1924) at Rosebud, Monroe County. An error 
occurs in the report of Gaige (1914); in this report of specimens from 
Richland County, T. carolina should read T. ornata, according to a per- 
sonal letter from Dr. Gaige to the writer. In this county, 7. ornata is 
reported to be very abundant. The writer has examined specimens from 
Fairfield, Centralia, Addieville, Pinkneyville, Robinson, and Litchfield; 
in the latter region this species of box turtle is very abundant. On 
November 4, 1930, a deluge of box turtles was mysteriously let loose on 
Michigan Avenue, Chicago. Eventually over 500 specimens were col- 
lected, consisting mostly of Terrapene ornata, with only a few specimens 
of T. carolina triunguis mixed in. Of these, about 500 specimens of T. 
ornata (no triunguis) were finally liberated by Dr. Karl P. Schmidt of 
the Field Museum, in the sandy area around Waukegan. Dr. Schmidt 
writes me under date of March 8, 1932: “Only a few of these survived 
the winter, and I doubt if the species ‘takes.’, All were marked with drill 
holes in the posterior rim of the shell.’” The fact of this planting should 
be noted, however, in case of the eventual appearance of the species 
around Waukegan. Where these turtles came from or how they got there 
is unknown, but it is believed that they were the chief performers in the 
thrilling sport of turtle racing, probably belonging to a “stable” the owner 
of which went broke. 


Hasirat.—Whereas Terrapene carolina carolina is distinctly an in- 
habitant of the deciduous woods environment, Terrapene ornata is a 
prairie species. It is found out in the open prairies or in sandy areas, 
wandering among the short grasses, and is very rare indeed in associa- 
tion with trees or heavy ground cover. Around Litchfield, Illinois, where 
the species is really very common, these box turtles are picked up in the 
open fields and pastures. While both 7. carolina and T. ornata are 
abundant in this region, their environmental preferences keep them re- 
markably apart in their distribution. 


Hasrts.—In general the habits of T. ornata are very similar to those 
of T. carolina which we have already discussed in some detail; hence we 
will be brief in our discussion of this species. Certain points of contrast 
in behavior should be considered. In our discussion of T. carolina we 
noted certain very marked tendencies toward an aquatic habit. Such 
tendencies seem to be entirely absent in T. ornata. We have seen that 
certain individuals of T. carolina took up a decided and definite home 
in the puddle of water at one end of the outdoor pen in which they were 
confined. While there were seventeen specimens of T. ornata in the 
same pen and these had the same range as carolina, not one was ever 
seen to enter the water. If one was placed in the water, it scrambled out 
as fast as it could and headed for the other end of the pen. One half of 
the pen is grown in herbaceous ground cover and bushes; the other end 


102 ILLINOIS BIOLOGICAL MONOGRAPHS 


is open and sandy. While T. carolina occasionally wandered, naturally, 
into the open end, the turtles of this species spent by far the greater part 
of their time around the “wooded” portion, and the reverse of this is 
equally true of T. ornata. 

In disposition there is also quite a noticeable contrast. While T. 
carolina is of a quiet and peaceful nature, yet it will snap on occasion. 
I have never seen T. ornata exhibit any defense reaction of this sort; 
in fact I have never been able to provoke it to the point where it would 
snap. It seems to have complete and absolute control of its temper and to 
have developed a completely fatalistic attitude. Its movements are more 
rapid than those of T. carolina, and its rate of progression is quite a bit 
faster. This may well be due to its lesser bulk, for it is a smaller turtle. 

I was able to compare the hibernation of these two box turtles in my 
outdoor pen. T. ornata goes into hibernation earlier than does T. carolina, 
for every specimen of this species had disappeared fully two weeks before 
the first of T. carolina showed a desire to hibernate. Once T. ornata has 
dug into the ground, it does not again emerge until spring. Like carolina, 
they start a few inches under the surface of the ground in October, and 
work their way deeper and deeper into the earth as the temperature of 
the soil drops. Whereas T. carolina ceases its descent at 19 inches, T. 
ornata went down to a depth of 2214 inches. This greater depth of 
hibernation is sufficient to account for the fact that the period of inactiv- 
ity is greater, and ornata does not emerge until a week or two after 
carolina has thawed out and become active. Thus it remains in hiber- 
nation nearly a month longer than carolina. 

Whether this species enters into temporary periods of aestivation or 
not is not clear, but there is a hint of it in a sentence by Ortenburger 
(1930): “In some instances they had burrowed partially into the mud of 
the river bank.” This at least hints strongly at the very similar but 
perhaps more definitely developed aestivation habit of T. carolina dur- 
ing the hotter parts of the summer. 


Nestinc Hazits anp Eccs.—I have no information at hand as to 
the breeding habits of T. ornata. While the females which I placed in 
my outdoor pen had (as seen in the dissection of certain individuals) 
large eggs in the ovaries, yet I find no young turtles. Either the turtles 
did not lay, or else the eggs failed for some reason to hatch. Perhaps 
this might be due to an insufficiency of direct sunlight in the pen. One 
specimen dissected had hard-shelled eggs in the oviduct. Most of the 
specimens of T. ornata, however, had the large eggs for that season’s 
laying still in the ovary at the time that all the females of T. carolina 
had hard-shelled eggs in the oviduct, indicating a somewhat later laying 
season. Since the rate of development in carolina is so slow (about three 
months) it is quite possible that, if the incubation period of ornata is 


THE TURTLES OF ILLINOIS—CAHN 103 


approximately the same, eggs laid in my pen may have been caught by 
the cool weather of the fall and hence not have hatched. It is quite 
certain that under normal and natural conditions, the eggs of ornata, 
laid in more open and exposed places, will receive a proportionately 
greater heat increment, and hence should perhaps have a shorter incuba- 
tion period to compensate for their later laying habit. The average size 
of the six hard-shelled eggs removed from the oviduct was 35 mm by 23 
mm. Data would seem to indicate that four to six eggs compose the 
usual clutch. 


Foop Hazits.—The stomachs of five specimens examined by me from 
Litchfield, Illinois, showed a purely vegetable diet. The mass of partially 
digested vegetable matter was beyond the possibility of identification, but 
no trace of insect remains or of other animal matter was discernible. On 
the other hand, Ortenburger (1930) has an interesting observation on 
the food habits of the species in Oklahoma: ‘“‘These turtles feed to a con- 
siderable extent on the grasshoppers of the region. Some of the queer- 
est sights seen were the attempts, often successful, of these supposedly 
slow-moving animals to catch grasshoppers. The movements are surpris- 
ingly quick and agile. On one occasion one turtle was seen to catch a 
large lubber grasshopper ‘on the wing’ by stretching the neck and literally 
jumping at the flying insect. Others were seen eating green caterpillars 
and robber flies.” 

Economic ImportaNce.—This turtle is not sufficiently abundant in 
the state to have any definite economic importance. Since, however, it 
has been shown to be an insect eater, whatever it does in this direction 
must be regarded by man as an asset. 


TABLE 9.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Terrapene ornata 
(Measurements in millimeters; weight in grams) 


Carapace Plastron Tail 
Specimen Head |———_———_| Weight | Sex 
No. 
Length | Width | Length} Width | Depth Total A-T 
112 91 111 73 a2 19 25 22 308 2 
103 85 103 66 49 18 24 Aa) 219 g 
96 ei 99 78 52 16 20 18 203 2 
96 83 98 71 48 17 32 20 202 a 
99 85 102 me 48 5 Wf 30 18 210 ou 
105 89 106 68 51 19 iat 17 320 2 
83 71 85 54 41 14 21 16 120 S] 
109 96 110 69 58 16 7) 19 295 2 
99 89 101 65 50 aly 21 16 231 2 


GENUS GRAPTEMYS AGASSIZ 


Emys (part) Duméril 1806 Malaclemys Gray 1844 
Clemmys (part) Wagner 1830 Graptemys Agassiz 1857 
Terrapene (part) Bonaparte 1830 Malacoclemmys Agassiz 1857 


104 ILLINOIS BIOLOGICAL MONOGRAPHS 


PLate 14—Graptemys geographica: A, Adult female, ventral view. B, Adult 
female, dorsal view. C, Newly hatched young, lateral view. D, Newly hatched 
young, ventral view. E, Newly hatched young, dorsal view. F, Immature female, 
lateral view. G, Adult female, lateral view. H, Head study of an adult. 


THE TURTLES OF ILLINOIS—CAHN 105 


Shell depressed, but with a distinct and conspicuous tuberculate keel. 
Bridge wide, with the axillary and inguinal elements well developed; 
inguinal anchylosed to the fifth costal scute. Top of head covered with 
a tightly drawn, smooth skin. Upper jaw without a median notch. 
Alveolar surfaces of the jaws very wide, but without a median ridge, the 
right and left sides separated from each other by a deep, narrow channel. 
Carapace strongly serrated posteriorly. Digits fully webbed. Tail rela- 
tively short. Choanae behind the level of the eyes. Skull with a bony 
temporal arch. The entoplastron les wholly anterior to the humero- 
pectoral suture. 


Graptemys geographica (LeSueur) 
(Geographic turtle; map turtle; ridge-back; slider; terrapin) 


Testudo geographica LeSueur 1817 Graptemys geographica Agassiz 1857 
Emys geographica Say 1825 Clemmys geographica Strauch 1862 
Terrapene geographica Bonaparte 1830 Malacoclemmys geographica Cope 1875 
Emys megacephala Holbrook 1844 Malacoclemmys geographicus Davis & 
Emys labyrinthica Duméril 1851 Rice 1883 


Description.—Shell oval, somewhat depressed, highest in the middle, 
but more elevated anteriorly than posteriorly and wider behind than in 
front of the middle; posterior margin serrated. Scutes of vertebral series 
all rather large. First vertebral weakly hexagonal, almost square, the 
anterior margins meeting in a wide median angle. Second and third 
vertebrals hexagonal, wider than long. Fourth vertebral hexagonal, the 
posterior margin about one-half of the anterior. Fifth vertebral pent- 
agonal and of good size. There is a mid-dorsal vertebral keel which is 
persistent throughout life, but which is much more pronounced in the 
young and partially grown individuals than in the large adults. This keel 
is blunt and tends to rise to a posterior tubercle which is inconspicuous 
in the adult; the curvature of the keel on each scute is uniform and 
regularly convex in front of the tubercle. Costal scutes large. First 
costal roughly trapezial, large; second the largest of the series, pentagonal, 
the median lateral margins encroaching between the second and third 
vertebrals; third costal similar to the second, but smaller, not as wide; 
fourth the smallest of the plastral elements (excluding marginals) and 
approaching square. There is a tendency for the scutes, particularly the 
costals, to exhibit longitudinal ridges in the form of obscure roughenings ; 
this feature is highly variable. Nuchal small, triangular, the posterior 
margin notched to receive the apex of the first vertebral. Marginals all 
large and wide, and with an even edge through the sixth. The seventh 
marginal increases in size posteriorly and the remaining five are notably 
larger than the anterior series, the eighth and ninth being the largest. 
Marginals serrated posteriorly from the eighth to the caudals, and there 


& 


106 ILLINOIS BIOLOGICAL MONOGRAPHS 


is a conspicuous notch between these latter scutes. Posterior marginals 
flaring, but the caudals with a vertical tendency particularly, at their 
median contact. The carapace is widest across the seventh and eighth 
marginals. Plastron large, truncate anteriorly, deeply and widely notched 
posteriorly. Gulars rather small, triangular, the anterior lateral angles 
slightly produced. Humerals trapezial, with the interhumeral suture the 
shortest of the mid-plastral contacts. Pectorals rectangular, the posterior 
lateral portion drawn out posteriorly to help form the bridge. Abdom- 
inals the largest of the series, square. Femorals the second largest of 
the plastral scutes, the lateral margin equalling the length of the abdom- 
inals, but the median contact shorter. Anals large, with a long interanal 
suture. Bridge wide, but rising only slightly toward the carapace, formed 
mostly by the prolongation of the abdominal and the posterior prolonga- 
tion of the pectorals. Axillary and inguinal elements large. Head large 
and massive and with a blunt snout. Both jaws with a smooth cutting 
edge, the margin of the upper jaw being somewhat sinuate and without 
a median notch. Alveolar surfaces of the jaws very wide, the inner edges 
almost meeting, and without a median ridge. Posterior articular surface 
of lower jaw expanded into a spoon-like dilation. Lower jaw flat, not 
hooked at the tip. Limbs large, strong, with the short digits fully webbed. 
Hind feet very large. Five digits of fore feet with a strong claw each; 
four digits of the hind foot with claws, the three inner being long and 
somewhat curved. Fore limbs covered with a series of large, sharp-edged 
scales; hind limbs with scattered scales, partially on the inner surface. 
Tail long. 

Cotoration.—The coloration of Graptemys geographica is highly 
variable; not only do adults show much variability, but individuals of 
different ages (sizes) have conspicuously different markings. The targe 
adult has the carapace dark olive-brown. There is a dark brown spot, 
almost black, at the posterior tubercle of each vertebral, and each of the 
costal elements is blotched irregularly with similar dark marks. There is 
a strong tendency toward a blotch on the sutures. Each dark blotch is 
encircled by a complicated pattern of pale yellow-green lines, these becom- 
ing very obscure in large specimens and increasingly conspicuous in 
younger individuals. Dorsally, each marginal has a dark blotch on the 
intermarginal suture, surrounded by the pattern of yellow-green lines. 
Plastron yellow, each suture lined in black. The wings of the pectorals 
and abdominals, together with the axillaries and inguinals, marked with 
black, irregular lines. The under surface of the marginals yellow, with a 
dark brown blotch on the intermarginal sutures, this blotch broken by 
enclosed irregular yellow lines. The blotches are more conspicuous and 
simpler from the seventh marginal backward; in front of the seventh the 
pattern becomes very complicated and general over the scute. Head, neck, 


THE TURTLES OF ILLINOIS—CAHN 107 


and limbs dark green, almost black, with lines and streaks of pale green- 
ish-yellow. Typical head markings as follows: A conspicuous greenish- 
yellow, comma-shaped dash behind the eye. A straight line extends from 
the tip of the snout to a point behind the eye, ending abruptly. A stripe 
starts at the anterior median margin of the orbit as a very thin line, 
widening behind the eye into a conspicuous stripe which extends down 
the neck. Numerous other longitudinal stripes parallel this one along the 
neck. A conspicuous vertical stripe crosses the tympanum, then turns 
abruptly to extend down the neck as a ventral lateral stripe. A straight 
median stripe starts at the symphysis of the lower jaw and ends 
abruptly at a point just posterior to the angle of the jaw. Horny portion 
of the jaws brownish. The entire ventral surface of the neck is covered 
with a series of longitudinal yellow stripes that tend to parallel each 
other. Limbs striped, the stripes more numerous ventrally, hence the 
limbs darker above than below. Remaining soft parts mottled in an 
intricate pattern. Iris golden green. 


Younc.—Specimen 35 mm carapace length: Carapace almost round, 
the length equalling the width. Shell highly arched, the posterior slope 
greater than the anterior. Vertebral keel prominent, particularly on the 
second and third vertebrals. Color dark green, with an elaborate pat- 
tern of yellow lines some of which are conspicuous and surround lines of 
lesser brightness. Marginals with a yellow circle at each intermarginal 
suture, this enclosing two (sometimes only one) yellow spots; each 
marginal with a vertical median yellow line and edged laterally with 
yellow, thus forming a yellow “T.” Plastron yellow, with irregularly 
placed and highly variable black spots and blotches. Under side of 
marginals yellow, with an intermarginal black spot containing a yellow 
center. Color markings of head, limbs, and soft parts typical of adult. 

Specimen 70 mm carapace length: The elaborate network of yellow 
lines on the carapace has increased in conspicuousness; ground color 
olive brown; markings on marginals in younger specimen. Plastral 
spots now becoming vague and poorly defined, blurred, fading. Keel on 
vertebrals prominent, tuberculate. 

Specimen 140 mm carapace length: Yellow reticulations of carapace 
becoming weaker, while the dark brown blotches are beginning to appear ; 
dark blotches on tubercles of the keel now well defined. Posterior serra- 
tions of marginals now deeper and very pronounced. Plastral markings 
practically obliterated, the dark lines along the sutures well established. 


Sex DIFFERENTIATION.—The head of the male is much smaller than 
that of the female, this character applying particularly to adults rather 
than to immature individuals. The tail of the male is much longer than 
that of the female, while the female attains a much greater total size than 
does the male. 


108 ILLINOIS BIOLOGICAL MONOGRAPHS 


GEOGRAPHIC DIsTRIBUTION.—Graptemys geographica has a distribu- 
tion encompassing most of the Mississippi Valley from Canada, Iowa, 
and Wisconsin southward to Oklahoma, Louisiana, and northeastern 
Texas. Eastward it extends through Pennsylvania to New York. Bab- 
cock (1919) finds it only along the eastern shore of Lake Champlain in 
New York, and notes its occurrence in Vermont. Surface (1908) gives 
numerous records for Pennsylvania, but points out that it is very local in 
its distribution. Morse (1904) says that it is common in Ohio in the 
larger rivers flowing into Lake Erie and into the Ohio River. In Indiana, 
Hay (1892) reports it generally over most of the state, and Evermann and 
Clark (1920) report it as by far the most abundant turtle in Lake 
Maxinkuckee in the northern part of that state. Ruthven et al (1928) 
report it from southern Michigan. For Wisconsin, Higley (1889) found 
it quite common in the southern part of the state, while Pope and Dickin- 
son (1928) limit it to the southern and western portions of the state, 
but Cahn (1929) did not find it in 
Waukesha County of southern 
Wisconsin. It is probably less com- 
mon in that state than formerly. 
Hurter (1911) records it from 
three widely separated points in 
Missouri, while Strecker and 
Hurter (1909) report it from 
Missouri and Texas, and mention 
its occurrence in the rivers of 
eastern Oklahoma. For Texas, 
Strecker (1915) reports it from 
the eastern half of the state. Patch 
(1925) extends the hitherto 
known northward range of the 


species into Canada with the re- 
port of specimens from Norway 
Bay, just west of Ottawa, Quebec, 
Guelph, and Point Pelee, Ontario. 

It~trNot1s Recorps.—Grapte- 
mys geographica has a_ general 
distribution over the entire state, 


but is confined to the larger rivers. Ce ie 

Yarrow (1882) records five speci- t” : 
mens from Mt. Carmel. Davis 
and Rice (1883) say that it is 
found throughout the state, and H. Garman (1889) says that this species, 
together with G. pseudogeographica, constitutes more than half the turtles 


Map 10.—Graptemys geographica. 


THE TURTLES OF ILLINOIS—CAHN 109 


of the Quincy region. McLain (1889) reports a specimen (1227) in the 
Stanford University collection from Plano, Kendall County. Garman 
(1892) reports it from Nippersink Lake, Green River in Henry County, 
Ogle County, Quincy, Peoria, Cairo, Pekin, the Little Wabash River, St. 
Francisville, and the Little Fox River at Phillipstown. Along the Missis- 
sippi, Hurter (1911) finds it in Madison, St. Clair, and Monroe counties. 
The Field Museum has a series of specimens from Havana (97, 334, 
476-80, 1767, 2193) and one from Jackson Park, Chicago (2925). The 
writer has examined specimens from the following localities: Mt. 
Carmel, Chester, Peoria, Metropolis, Havana, Pekin, Meredosia, Ster- 
ling, Rock Island, Quincy, the Kankakee River at Kankakee, Bureau, 
Beardstown, Fox Lake, Okawville, Vandalia, Murphysboro, and Horse- 
shoe Lake in Alexander county. 


Hasitat.—An abundant turtle throughout the state, frequenting most 
commonly the lakes and larger rivers, this species is less often found in 
the smaller streams. In over-flow ponds along the courses of the rivers 
they often occur in large numbers, but they leave these for the rivers 
themselves if the ponds begin to dry up. Garman (1892) says that “half 
the individuals which one may see perched on logs during a day’s boating 
in August would prove to be of this species.” The present writer believes 
that this species is less numerous than formerly, yet distinctly more com- 
mon than the next, closely related, species. These turtles prefer water in 
which grows an abundance of such vegetation as Chara and Nitella, and 
this is utilized to the utmost for concealment in time of danger and affords 
the hunting grounds for their food supply. They are seldom found in 
clear water and very rarely indeed in swift flowing streams, unless it be 
during temporary periods of flood or high water. Large, swift rivers, 
like the Mississippi and the Illinois, and especially the backwaters of 
these, with soft bottoms, afford an ideal environment, and in such places 
the species finds its optimum. 

Hasits.—Graptemys geographica is highly aquatic in its habits. Its 
strongly webbed feet afford it excellent propellors, but the bulk and 
weight of the shell are such that it is not a fast swimmer. The hind feet 
are particularly large and drive the turtle at a reasonable speed. On land 
the turtle is slow, awkward, and evidently ill at ease. It is found on 
land only during the breeding season and under such unusual circum- 
stances as may drive it from one pond or river to another. If caught on 
land, the head is withdrawn with a hissing sound caused by the expulsion 
of air from the lungs accompanying the withdrawal of the head and neck 
within the shell. If provoked it emits an occasional hiss as the head is 
withdrawn farther and farther into the protective position. Wary and 
cautious while in the water, on land the turtle is timid and very inoffen- 


110 ILLINOIS BIOLOGICAL MONOGRAPHS 


sive despite the power and strong cutting edges of the jaws. Both the 
structure of the jaws and the powerful musculature thereto attached 
would enable it to do serious damage were its disposition less retiring. 

These turtles are among the earliest to make their appearance in the 
spring. The coldest months of the winter may be spent in the mud at 
the bottom of the river or in the soft banks; occasionally muskrat run- 
ways are utilized, the turtles either burying themselves in the soft floor 
of the passage or remaining half concealed in the runway itself. Shortly 
after the ice goes out they are found basking on the shore at the very 
edge of the water. Those which hibernate in shallow lagoons or ponds 
come out first, for here the water warms up earlier than in the bed of 
the larger rivers. At this time they are slow and sluggish and may be 
easily caught. They love the sunshine, and spend hour after hour lying 
motionless as they absorb the heat. With the first chill of later afternoon 
they disappear into the water, but as April wears on they remain out 
longer and longer. They are highly gregarious and usually found in 
close association with their own kind. This gregariousness makes them 
difficult to approach, for when one becomes frightened and slides into 
the water, all promptly become panic stricken and disappear likewise. 
During the long summer days they bask luxuriously upon logs well out 
in the water, lying with the hind legs outstretched. Through field glasses 
they may be seen snapping at passing insects, many of which they suc- 
ceed in catching. With the approach of fall their basking periods are 
shortened, though these turtles are among the very last to go into hiberna- 
tion. There is some evidence that occasional individuals do not hiber- 
nate at all, but remain slightly active on the river bottom all winter. 
Along the banks of the Illinois River I have found dozens of young 
specimens that fell victim to this disinclination to hibernate. They had 
remained out of water too long: numbed with the cold, they were unable 
to regain the water; stranded, they froze to death. 


Nestinc Hasits.—Late in May, and from then until mid-June, the 
females come out to lay their eggs. Their timid disposition leads them to 
come out very early in the morning, for they prefer solitude, and day- 
light finds the turtle well on its journey. The female comes out of the 
water slowly but there is an air of stolid determination about her. She 
wanders about in a zigzag path for some time, often getting far from 
water in her search for the exactly suitable nesting site. The moist sand 
of the shoreline interests her not in the least. One may sometimes follow 
her tracks if the ground is suitable, and the aimlessness of her wandering 
is quite evident from the great irregularity of her course. Here she 
pauses to dig: a small rock interferes, so she goes on. Here she tries 
again, but a small root is in the way, so she gives it up and wanders on. 
Here she digs again, but some undefinable thing does not suit her— 


THE TURTLES OF ILLINOIS—CAHN 111 


perhaps the soil was not just right—so she goes on again. Aiter hours 
of search and many efforts at digging, the right spot is found and the 
nest is dug. This is a symmetrical flask-shaped cavity of a diameter suffi- 
cient to admit her, dug with the hind feet only, the front feet being used 
as a brace. The length of the neck and the size of the flask depend upon 
the character of the soil selected and the number of eggs to be produced. 
I have seen dozens of nests of this species but never yet one that was 
not well filled, nor one that was over full. Once the digging has begun 
in earnest, the female is determined to go on with it to the end; if dis- 
turbed, she watches the intruder for a time, but does not retreat, and 
when things quiet down she resumes her work. The eggs are laid in a 
double layer in the body of the flask, often with a thin layer of dirt 
between the eggs. In the neck of the flask are deposited the last two or 
three eggs, the last egg laid being very close to the surface. The loose 
dirt is then scraped into and over the hole and the surface smoothed by 
dragging the plastron over the small area disturbed so as to erase the least 
trace of the disturbance. 


Eccs.—The number of eggs deposited varies from ten to sixteen, 
depending upon the size and age of the turtle, with twelve to fourteen 
by far the commonest number. They are white and elliptical, with a soft, 
leathery shell which may be very easily indented. They average 32 mm by 
21 mm. The rate of development is slow, the young hatching usually 
about mid-August or shortly thereafter. The young dig themselves out, 
coming up through that position of the ground occupied by the nest, this 
affording them the least resistance. Once at the surface they blink the 
dirt out of their eyes and head straight for the nearest water, even 
though it be a quarter of a mile or more away and may take a week to 
reach. Newman (1906) reports newly hatched young in May, and 
explains it in reference to unusual females found laying in late July, 
saying that the “well advanced embryos must pass the winter in a condi- 
tion of dormancy analogous to that observed in hibernating adults.” I 
have in my collection several newly hatched young taken in the vicinity 
of Meredosia on the Illinois in early July. There seems to be no reason 
why a well developed embryo should not live over the winter within the 
egg; the dropping of the temperature slows up the rate of development 
and the embryo remains in status quo until the warmth of spring pene- 
trates to the eggs, whereupon it resumes its development. Furthermore, 
turtles are poikilothermous. Whether those eggs in the neck of the nest, 
only an inch or two beneath the surface, hatch after a thorough freezing 
is undetermined. 


Foop Hasits.—The great width of the masticatory surfaces of the 
jaws are admirably suited for cracking mollusks, and stomach examina- 
tions show a very large percentage of these animals in the diet. Snails, 


112 ILLINOIS BIOLOGICAL MONOGRAPHS 


and an occasional insect or larva, are the main items of food taken. So 
badly crushed are molluscan remains that identification is almost impos- 
sible. Besides this fact, the hard parts of the shell are scratched out of 
the mouth by means of the claws of the front feet. Newman (1906) 
makes an interesting observation: ‘Two methods of feeding prevail. The 
favorite method seems to be to capture the mollusc when the foot and 
gills are well out of the shell, to bite off the soft parts and leave the hard 
shell. To do this the final closure of the jaws must be quite sudden. If 
they fail to secure the body of the snail in this way, they adopt the crush- 
ing method.” I have frequently watched this species prowling slowly 
about amid the vegetation looking for snails, and thick beds of aquatic 


TABLE 10.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Graptemys geographica 
(Measurements in millimeters; weight in grams) 


Speci Carapace Plastron 
Awa Head | Tail | Weight] Sex 
: Length| Width | Length| Width | Depth 
1 Sia ere 227 170 196 103 84 33 86 ae Q 
Dye ules 203 181 213 141 85 34 79 1687 g 
eee 203 158 183 113 i 31 60 1055 g 
pera ree 190 141 169 118 66 29 71 780 iS) 
een 186 140 168 110 63 33 68 740 g 
Oissracierere 151 126 142 96 53 26 61 498 oe 
i rere ann 133 98 115 57 41 19 71 ia fou 
Once 118 97 106 54 42 17 40 g 
Dos Vousavoncna 116 87 101 48 37 17 65 fof 
103.0463 ae 113 86 98 47 36 16 63 os 
1 ee tee 106 82 90 43 35 15 62 ou 
1D eie cei 70 62 61 32 27 13 22 9 
1304 chek 38 32 35 21 16 9 19 fou 


Text-FiGurE 15—Drawings of lower jaws, showing differ- 
ence in alveolar surfaces. A—Graptemys geographica; B— 
Graptemys pseudogeographica pseudogeographica. 


THE TURTLES OF ILLINOIS—CAHN 113 


plants are often thoroughly tunneled by pathways made by these turtles in 
search of their food. In the laboratory they refuse every kind of food 
except snails and clams, showing almost a total lack of the scavenger 
habit so often found among turtles. 

Economic ImporTANCE.—Graptemys geographica is caught in great 
numbers by net fishermen, but does not often reach the public market, 
probably because it seldom reaches a size sufficiently large to warrant 
shipment. The larger specimens, however, are excellent for the table. 
The flesh is entirely palatable, and except for the size there is no reason 
why they should not be used as food. 


Graptemys pseudogeographica pseudogeographica (Gray) 

(Ridge-back ; map turtle; saw-back; slider; “‘terrapene’”’; river terrapin) 

Emys lesueurii Gray 1831 

Emys pseudogeographica Gray 1835 

Emys geographica (part) Duméril & Bibron 1835 

Graptemys lesueurti Agassiz 1857 

Graptemys pseudogeographica Gray 1863 

Clemnys pseudogeographica Strauch 1865 

Malacoclemmys pseudogeographicus Cope 1875 

Malacoclemmys lesueuri True (in Yarrow 1882) 

Malaclemys pseudo-geographica Hay 1892 

Graptemys pseudogeographicus Paulmier 1902 

Graptemys pseudogeographica pseudogeographica Stejneger & Barbour 1923 

DeESCRIPTION.—Shell oval, somewhat depressed, rather flat-topped in 

fully grown specimens, highest in the middle, emarginate posteriorly. 
Carapace with a conspicuous persistent vertebral ridge rising to a prom- 
inent posterior tubercle which is well developed upon the second and 
third scutes. Vertebrals five, the first the smallest of the series. Second 
and fourth vertebral scutes of approximately the same size, hexagonal ; 
the anterior margin of the second is shorter than the posterior and this 
is reversed in the fourth scute. The third is the largest of the series, 
hexagonal, the anterior and posterior margins about equal. The fifth 
vertebral is variable in form, sometimes being rather “maple-leat’’-shaped, 
the total length, however, about equalling the maximum width of the 
scute; this maximum width is attained by wing-like lateral projections 
which intrude deeply between the fourth and fifth costals—if a fifth is 
present. If but four costals are present the fifth vertebral is pentagonal 
and wider than long. The keel is low and inconspicuous on the first 
vertebral. On the second it begins to rise at about the middle of the 
scute and reaches a sharp posterior tubercle at the very posterior edge 
of the scale. On the anterior portion of the third vertebral a low ridge 
drops from the apex of the anterior tubercle toward the middle of the 
scute and rises again to a conspicuous tubercle at the posterior margin, 


114 ILLINOIS BIOLOGICAL MONOGRAPHS 


giving a concave profile to the keel which is particularly obvious on the 
third (and much less so on the second) vertebral scute. The number of 
costals shows some variation; the usual number is four, but occasionally 
five are present. If five, the fifth vertebral is drawn in, as described 
above, in order to make room for it. Costals large. First costal large, 


PLATE 15.—Graptemys pseudogeographica pseudogeographica: A, Adult, ventral 
view. B, Adult, dorsal view. C, Adult, lateral view. D, Newly hatched young, 
lateral view. E, Newly hatched young, ventral view. F, Newly hatched young, 
dorsal view. G, Head study of an adult. 


THE TURTLES OF ILLINOIS—CAHN 115 


roughly triangular. The second is the largest of the series and is wider 
than long; the third is of the same shape and proportions as the second, 
but somewhat smaller. The fourth is roughly rectangular if a fifth is 
present, but approaching square if only four are present. If a fifth is 
present it is by far the smallest of the series. Nuchal with a posterior 
notch to accommodate the anterior angle of the first vertebral. Thirteen 
pairs of marginals. First marginals with the median border much shorter 
than the lateral, giving the appearance of a “bow tie” to them and the 
enclosed nuchal. There is a slight serration associated with the first two 
anterior scutes. The marginals begin to flare widely at the eighth, from 
which point the edge of the carapace becomes increasingly more serrated 
posteriorly. Caudals rise sharply toward their median symphysis and 
contain a sharp, deep posterior notch. Plastron large and strong, the 
anterior and posterior lobes being of approximately the same length 
and width, truncate anteriorly and widely emarginate posteriorly. Gulars 
triangular, the length equalling the width. Humerals with the inter- 
humeral angle the shortest of the plastral sutures. Pectorals rectangular. 
Abdominals nearly square, the largest of the ventral elements. Femorals 
next to the abdominals in size, the lateral margin equalling the length 
of the abdominals but with the median contact shorter. Anals large, the 
interanal suture longer than the interfemoral; the anal notch is wide and 
generally rounded. The bridge is wide and flat, rising but little toward the 
carapace. Axillary and inguinal elements large and well developed. Head 
medium to large, depending upon the sex of the specimen; snout not 
protruding. The cutting edge of the upper jaw is smooth and slightly 
convex and without a notch; lower jaw with the cutting edge slightly 
convex and without a hook. Alveolar surfaces moderately wide, wholly 
separated in front by soft skin. The limbs are well developed, the hind 
limbs being particularly strong and well developed. Digits fully webbed 
to the base of the claws. Five digits on fore limb, each with a claw; four 
digits only of the hind foot with claws, the fifth lacking a claw. Tail 
rather short, pointed. 


CoLoraTion.—In fully adult specimens the carapace is olive green, 
sometimes with a brownish cast. Each costal and many of the marginals 
exhibit a dark brown, almost black posterior blotch; there is a tendency 
for each blotch to be encircled by a yellowish or greenish line. The 
vertebral keel is dark brown, darkest at the tubercle. Scutes of the 
carapace with irregular network of yellowish or greenish reticulations 
or tracings; these reticulations are often rather obscure in large (old) 
specimens. The plastron of the large adult is yellow, with a varying 
amount of vague, dusky discoloration which may be totally absent; 
younger specimens show a bilateral pattern of dark areas enclosing 
yellow markings within, reminding one somewhat of Chrysemys picta 


116 ILLINOIS BIOLOGICAL MONOGRAPHS 


bellu. Bridge marked with dusky, tending toward longitudinal lines. 
Axillaries and inguinals either lined or blotched with dusky discolora- 
tions. Marginals irregularly marked with a dusky color on the ventral 
surface. Head dark olive green, elaborately marked with yellow lines. 
3ehind the eye is a conspicuous yellow transverse streak which, medially, 
turns posteriorly to extend down the head and neck parallel to the 
streak from the opposite side. On the head it has the appearance of a 
boomerang. Sometimes this mark is carried down below the eye. A 
straight yellow line extends from the tip of the snout to well behind the 
posterior margin of the eyes, terminating between the angles of the 
boomerang. Below the eye is a small yellow spot. The remaining portions 
of the head with fine yellow lines, many of which extend down the neck 
parallel to each other. Jaws mottled with yellow. There is a yellow spot 
at the symphysis of the lower jaw. Limbs, tail, and the remaining soft 
parts olive green, elaborately lined with yellow. 


Younc.—In very young individuals (32 mm) the shell is almost per- 
fectly round. Carapace very high, with a steep lateral slope; anterior 
slope abrupt; posterior slope more gradual. Keel very conspicuous, par- 
ticularly on the second and third scutes, but without any trace of the 
concave profile. Marginals all more or less in line with the general curva- 
ture of the carapace. Posterior marginals not only with an intermarginal 
notch but with a strong tendency toward a second notch in the middle of 
the edge of each scute, giving the border a very “‘saw-toothed” appear- 
ance. Color bright green, with conspicuous yellow tracings; the dark 
mark upon the keel of the vertebrals conspicuous. Plastron with a 
bilateral dusky pattern on yellow, with numerous yellow inclusions. Sur- 
face of the carapace finely granular. As the turtles grow larger the 
shape and pattern tend toward that of the adult. In a larger specimen 
(102 mm) the dark blotches on the costals and marginals are beginning 
to appear, the color is now brownish and the yellow tracings still con- 
spicuous, especially about the forming dark blotches. There is still a 
faint trace of the toothing of the anterior marginals, but the tooth in the 
middle of the border is growing very weak. The concave profile of the 
keel is now plainly evident. Bilateral plastral markings still plain but 
fainter than in the newly hatched young. 

Sex DIFFERENTIATION.—The head of the male is relatively smaller 
than that of the female, which is quite massive. The tail of the male is 
longer than that of the female, thus extending the anus beyond the 
posterior margin of the carapace. 

COMPARISON OF THE Two Species oF GRAPTEMysS.—Although io the 
uninitiated there seems to be considerable difficulty in separating Grap- 
temys geographica from Graptemys pseudogeographica pseudogeograph- 
ica, there are certain differences which usually will make the distinction 


THE TURTLES OF ILLINOIS—CAHN 117 


less difficult. These differences have been ably discussed by Garman 
(1890). We may summarize them as follows: 

1. Head.—Large, massive in G. geographica, contained about 4.6 times in the 
length of the carapace; small to medium in G. pseudogeographica, contained in the 
carapace about 6.4 times. 

2. Jaws —Alveolar surfaces of G. geographica greatly expanded, while this is 
not the case in G. pseudogeographica (see Text-fig. 15). 

3. Vertebral Ridge—In G. geographica the median vertebral ridge is obscure, 
flattened, and in profile a simple curve and not of the tuberculate type; in G. 
pseudogeograplica this ridge is very prominent, tuberculate, and exhibiting a con- 
cave profile on at least the third scute. 

4. Spot Behind Eye—In G. geographica this spot is not comma-shaped; it is 
isolated and is directed longitudinally. In G. pseudogeographica it is comma- 
shaped or like a boomerang, not isolated, being continued as a fine stripe down the 
neck. 

5. Mandibular Spot.—There is a yellow stripe on the symphysis of the mandible 
of G. geographica, while this mark is in the form of a yellow spot in G. pseudo- 
geographica. 

6. Supraoccipital Spine—Though purely an osteological character, G. geo- 
graphica has an enlarged, thickened supraoccipital spine, while G. pseudogeo- 
graphica shows a small, unthickened spine. 

GEOGRAPHIC DISTRIBUTION.—Graptemys pseudogeographica pseudo- 
geographica is distributed over the Mississippi Valley from Wisconsin 
and northern Iowa southward, and from eastern Kansas and Oklahoma 
eastward to Ohio and Alabama. Thus it is seen to have a more circum- 
scribed range than Graptemys geographica. To the east of Llinois it is 
reported from Columbus, Ohio, by Yarrow (1882), though it is not 
included in the state list by Morse (1904). It is not listed by Ruthven 
et al (1928) from Michigan. Blatchley (1891) lists it from Indiana, 
while Hay (1892) reports it from several localities in that state. The type 
locality is the Wabash River at New Harmony, Indiana, which is just 
across the river from Illinois. In Wisconsin, Hoy (1883) reports it as 
not rare, while Higley (1889) says it is quite common in the southern 
half of the state; Cahn (1929) did not find it in Waukesha County. 
Pope and Dickinson (1928) refer it to the western part of Wisconsin. 
In Missouri, Hurter (1911) gives numerous records, while in South 
Dakota, Over (1923) reports it only from the Missouri River, which 
it no doubt ascends from the Missouri region. Yarrow (1882) gives a 
single record for Kansas, as does Burt (1927) for that state. In the 
south its place is taken by two sub-species, G. pseudogeographica kohnii 
and G. pseudogeographica oculifera. 

Ittinots Recorps.—For Illinois, Garman (1892) says: “Throughout 
the state, but less common north,’’ and gives records from Quincy, 
Jersey County, the Wabash Valley, the Ohio River, and Cairo. In his 
paper dealing with the Quincy region (1888) he says that the two species 


118 ILLINOIS BIOLOGICAL MONOGRAPHS 


of Graptemys constitute about 
half the turtles seen, while in his 
short notes (1892) he reports it 
as “very abundant in all our 
rivers.” It is not mentioned by 
Hankinson (1917) for the 
Charleston region, while Davis 
and Rice (1883) say that it is 
found in all parts of the state. 
With the records mapped, it ap- 
pears that Garman’s statement of 
1892 is nearest correct at the 
present time. The Field Museum 
has specimens from Havana 
(£95, 331, 475, 1759, 1773), Mc- 
Henry (#2670), and Maeys 
(#3464, 3465). Hurter (1911) 
reports it from Madison, St. Clair, 
Monroe, and Randolph counties. 
The writer has examined speci- 
mens from the following places: 
Chester, Havana, Meredosia, 
Quincy, Grafton, Carlyle, Okaw- 


ville, Murphysboro, Metropolis, 


: y Map 11.—Graptemys pseudogeographica 
Mt. Carmel, Elizabethtown, onaionencraniies 


Horseshoe Lake in Alexander 
County, and Carmi, which is only a few miles from the type locality. 


Hasirat.—This abundant turtle within the state is distinctly of 
aquatic habits; indeed, so strictly does it remain in the water that it is 
usually referred to in the literature as “eminently aquatic.” It is found 
in lakes, ponds, sloughs, and larger rivers, and is about equally abundant 
in all of these types of habitats. It is more common in waters abundant 
in bottom vegetation among which the turtles delight in wandering, and 
distinctly less common in the clearer waters. It is absent from lakes 
lacking this dense vegetation, or at least from those regions of the lake 
in which the vegetation is absent, and is not found with any frequency 
in rivers with any considerable current. This environmental preference 
perhaps explains in part the distinctly southern distribution of the species 
in Illinois, for in the southern portion of the state these aquatic condi- 
tions, congenial to G. pseudogeographica, are of more frequent occur- 
rence. It would appear, also, that the species is more delicately attuned in 
its environmental preferences than the preceding species, for it is less 
hardy and distinctly shorter lived under adverse conditions. 


THE TURTLES OF ILLINOIS—CAHN 119 


Hasits.—The entire structural make-up of this turtle seems to em- 
phasize its highly aquatic nature. The feet, especially the hind feet, are 
large and powerful, and the toes are fully webbed, making excellent 
structures of propulsion. The shell is large and relatively quite heavy, 
making the turtle rather awkward when out of its preferred element. 
In the water it is wary and secretive, disappearing from view at the 
least sign of danger, and remaining beneath the surface amid the protec- 
tion of the dense vegetation for a long period before reappearing. These 
turtles are very gregarious and are often seen basking lazily in the hot 
sun. Basking places well away from the shore are best liked, and a 
protruding dead-head or a stranded log is ideal from their point of view. 
If such a site is not available, they will line up on half submerged logs 
along the shore, but under such conditions the turtles are more than 
ordinarily wary and on the alert, seeming to sense the added dangers 
which proximity to the shore brings. At the least sign of disturbance 
every turtle slides into the water, and this characteristic action has given 
to them the local name of “sliders.” If caught on shore they behave 
much as do the turtles of the preceding species, withdrawing within their 
bulky shell and remaining stubbornly retracted. After having poked 
around for a few minutes at one I once caught on shore, I left it high 
and dry on the bank; returning about an hour later, the turtle was still 
in the same spot and had only reached the stage of renewed hope which 
permitted it to have its legs relaxed and its nose out about half an inch. 

In the northern part of the state this species goes into hibernation 
during October and remains inactive until after the ice has gone out. 
The turtles bury themselves to a depth of from four inches to a foot 
or more in the soft mud of the bottom, or crawl into the under-water 
entrances of muskrat houses and there bury themselves. In the southern 
part of the state the turtles do not go into hibernation at all, but remain 
active, though but sluggishly so, throughout the coldest months of the 
winter. There is a hint that during this time they do not feed, or at least 
feed sparingly, for such turtles taken in the winter have invariably had 
the stomach empty. With the warming of the water in the spring, the 
turtles, as G. geographica, come out and sun themselves during the 
brightest hours of the day. The first chill of the afternoon sends them 
back into the water, yet occasionally an individual is found in which the 
reaction time to the change in temperature was too slow to get it back 
into the protection of the water before paralyzed by the cold. Such an 
individual seems always to die with one night’s exposure. Such incidents 
are perhaps more common prior to hibernation in the fall than in the 
spring following it, though both have been observed. 


Nestinc Hasits.—The literature is strangely silent regarding the 
breeding habits of this turtle, the frequently cited reference being to 


120 ILLINOIS BIOLOGICAL MONOGRAPHS 


Agassiz (1857): “The time of the year at which they [turtles] lay is 
the same for both the northern and the southern species, without refer- 
ence to physical differences, such as temperature, moisture, etc., of 
climate in general. Graptemys LeSueurii [G. pseudogeographica], which 
lays as early as the first of June, gives the earliest instance of incubation 
in the year.’ The standard reference to laying on June 1 at Natchez, 
Mississippi, follows as the stock example. This statement, widely quoted 
as it is, seems hardly to hold as a set rule; certainly it does not hold for 
the observations made at Meredosia in the summer of 1931. At that time, 
with many turtles of other species laying throughout June, it was not 
until July 6 that G. pseudogeographica began to lay. From June 13 on, 
females of the species with eggs mature but without the shell were 
found, but not a trace of evidence exists that the species laid prior to the 
July date. On July 6, then, a female with a carapace length of 218 mm 
was watched during her nesting progress. From the field notes I read: 
“The nesting site was in the middle of an old road, between the ruts 
made by the wagon wheels. The road runs about thirty feet from the 
river on one side and along a ditch about twenty feet away on the other. 
The soil is black and fairly solid. The turtle had a heavy growth of 
algae on her shell, and may well have come out of the ditch which is 
full of algae. She had apparently started digging but a few minutes 
before, judging from the rapidity with which the rest of the nest was 
dug. During the observed digging of the nest, which lasted five minutes 
(probably not over ten minutes was required for the entire excavation) 
the turtle worked with great rapidity, standing in one position. The 
hole was dug with the hind feet only, by scratching vigorously with legs 
alternating. As soon as a little pile of loose dirt accumulated, she pushed 
it out behind her, using both legs together to shove it out of the hole, 
the dirt coming in contact with the soles of the feet. The hole descended 
forward at an angle of 60° under her position, the sloping floor of the 
hole being the inclined plane up which she pushed the loose dirt. As 
she started to lay she slowly rotated her position to the right, pausing 
periodically to lay an egg or two, after which she rotated again. With 
all the eggs laid she was back almost where she started from, having 
rotated through about 350°. From this position, then, she reached back 
with one hind leg after the other and, using the anterior (top) of the 
feet, she raked the loose dirt piled immediately behind her into the hole 
and filled it completely. For a few moments she patted the dirt down 
with the soles of her hind feet, then headed back toward the ditch, and 
was captured. The actual time occupied in laying, as represented by the 
rotation through 350°, was just seven minutes. The hole was then care- 
fully opened. The nest was 514 inches deep, with a 2-inch opening at the 


THE TURTLES OF ILLINOIS—CAHN 121 


surface, and terminated in a rounded chamber at the bottom 3 inches 
in diameter. It contained eleven eggs.” 


Eccs.—The number of eggs laid varies from seven to thirteen, with 
nine or ten being the most common number. They are white, elliptical 
in shape, and covered with a soft, leathery shell of fine texture. The 
eleven eggs laid by the female whose nesting has been described above, 
measured as follows (in millimeters): 30x 20, 32x 21, 30x 21, 32x 20, 
$3023, 33x21, 33x22; 31x21, 34x23, 29x20, 32x20. This set 
averages a trifle smaller than other sets on hand; the average of 71 eggs 
representing 7 complete egg complements, is 32.7 x 22.5 mm. I have no 
information in regard to the incubation period, but young of the species, 
certainly not very long out of the egg, have been taken in late August 
and early September. 

Foop Hasits.—Unlike many other species of turtles, G. pseudogeo- 
graphica is almost exclusively a vegetarian when adult, therein showing 
a very striking difference when compared with the closely related G. 
geographica. The young turtles are both carnivorous and herbivorous in 
habits, but when they reach a carapace length of 120-130 mm, the car- 
nivorous tendencies diminish and soon disappear. The young feed largely 
if not exclusively upon small mollusks, principally thin-shelled gastro- 
pods, with an occasional worm or insect larva thrown in. Stomach ex- 
aminations of ten adult specimens showed quantities of chewed-up 
aquatic grasses, succulent stems and bulbous roots, with no trace what- 
ever of animal matter. The bulbs of a sedge have been frequently identi- 
fied. As has been noted, G. geographica is largely a mollusk eater, and 
although both species show similar habitat preferences and are found 
often in close association, the masticatory apparatus of the two species 
clearly indicates their divergent gastronomic preferences. The alveolar 
surfaces of G. pseudogeographica are not expanded or especially adapted 
for the crushing of mollusks, and the turtles attempt no such action 
except when young and then only upon small “‘paper-shelled”’ species. 
The species is not scavenger. Surface (1908) says, “little is known 
concerning the food and feeding habits of this turtle, excepting that it 
is said to feed upon very small fish, reptiles, etc.” The writer has no 
evidence that would bear out this surmise. Although dozens of speci- 
mens have been kept alive in the laboratory, they would never touch 
meat of any kind in any form, but ate lettuce and greens sparingly. They 
fed only when submerged and could never be induced to eat while out of 
water. 

Economic Importance.—Along the Illinois River, the chief source 
of turtles that “go to market’ from the state, the most prized and sought 
for species are the snapper and the soft-shells, because of their large 


122 ILLINOIS BIOLOGICAL MONOGRAPHS 


size. Next to these follows G. pseudogeograplica, with Pseudemys 
elegans fourth. The fact that these turtles reach a reasonably large size 
when compared to other species of “terrapins” explains its presence in 
the turtle markets. Clark and Southall (1920) say: “the terrapin [G. 
pseudogeographica| were used as a substitute, or partial substitute, for 
the diamond-backs, and that for this purpose the males were not de- 
sired. What was wanted was the egg-bearing or ‘queen’ terrapin. .... 
During the summer of 1918 ‘queen’ terrapin were being quoted at that 
place [the Illinois River] at $1 each.” They reach a weight of from 
two to three pounds frequently, and are exceedingly good for eating. 


TABLE 11.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Graptemys 
pseudogeographica pseudogeographica 
(Measurements in millimeters; weight in grams) 


Speci Carapace Plastron 
Ne Head | Tail | Weight! Sex 
: Length} Width | Length} Width | Depth 
Lees 220 163 198 93 76 28 70 1721 Q 
Doreen 203 152 185 85 65 31 69 1119 fof 
See rane: 195 149 181 83 63 Qi 55 984 Q 
AN Werctoiene 192 148 179 85 66 29 71 968 - 
Seeeegee: 185 153 179 80 67 28 50 788 fof 
(Hareueree 178 135 170 72 69 25 50 540 Q 
Tee Save. 116 86 101 63 38 17 65 158 fof 
Sertianrad.s 101 84 94 63 39 17 61 127 rofl 
senna 95 75 82 56 34 16 30 103 oy 
OME 92 M2 80 53 32 14 52 95 of 


GENUS CHRYSEMYS GRAY 


Emys (part) Duméril 1806 Chrysemys Gray 1844 
Terrapene (part) Bonaparte 1830 Clemmys (part) Wagler 1862 
Alveolar surface of the jaws narrow, but slightly wider posteriorly; 

median ridge inconspicuous and the alveolar groove poorly defined in 
the anterior part of the jaw. Upper jaw with a median notch, lateral 
to which is a small tooth-like projection; lower jaw with a small tooth- 
like projection which fits into the upper median notch. Shell wide, much 
depressed ; usually smooth, but in some cases with concentric rugae; no 
keel is present. Toes strong and fully webbed; hind feet large, spread- 
ing; claws strong, curved. Carapace and plastron united by a suture 
and supported by a strongly developed axillary and inguinal element ; 
inguinal united to the fifth costal plate. Entoplastron anterior to the 
humero-pectoral suture. Skull with a well developed temporal arch; 
choanae between the eyes. Dorsal surface of. the head covered with 
plain, tightly drawn skin, 


THE TURTLES OF ILLINOIS—CAHN 123 


The Chrysemys Problem 


From the point of view of the genus Chrysemys, Illinois is a region 
of great interest and still greater complexity because of the overlapping 
of the range of the several subspecies. Chrysemys picta was described 
by Schneider in 1783, and was characterized by the transverse arrange- 
ment of the costal and vertebral scutes plus the clear yellow plastron. 
In 1831 Gray described Chrysemys belli, characterized, as are all the 
members of the group other than fpicta, by the alternate arrangement of 
costals and vertebrals, and by the great development of the dark area of 
the plastron. In 1857 Agassiz described Chrysemys marginata, charac- 
terized by the greatly restricted dark area of the plastron, and Chrysemys 
dorsalis, with an immaculate yellow plastron and a conspicuous median 
dorsal red stripe down the vertebrals. The last of the genus to be de- 
scribed is Chrysemys treleasei, which Hurter described in 1911, dis- 
tinguished from the other species by the red color of the plastron. Sub- 
sequently bellii, dorsalis, and treleasei were reduced to subspecies of 
marginata, Chrysemys picta remaining the second species of the genus. 
In their review of the genus Chrysemys, Bishop and Schmidt in 1931 
established what they term the ‘‘intergradation” of Chrysemys picta otf 
the Atlantic states with what was designated as Chrysemys marginata 
marginata whose range extended from New York to the Mississippi. 
Babcock (1933) points out the eastern extension of the intergrading 
of Chrysemys picta marginata with C. p. picta “through New England 
to the Atlantic coast.” He gives intergrade records from Massachusetts 
(including Pasque Isle and Nantucket), Vermont, New Hampshire, and 
Maine. Since picta is the older name, the eastern species becomes 
Chrysemys picta picta, and the original marginata now becomes picta 
marginata because of these intermediate forms. Stejneger and Barbour, 
however, do not accept this in their 1933 revision of their Check List; 
nevertheless, the present writer proposes to follow them in their termi- 
nology. Bishop and Schmidt show the intergradation of the aligned verte- 
bral and costal scutes of picta picta to the alternate arrangement found 
in picta marginata, as well as the development of the plastral markings. 
These writers also call attention to the intermediate conditions found in 
the Chrysemys from northern and central Illinois, where the subspecies 
marginata and bellii overlap, and mention a possible intergradation of 
these with picta dorsalis “somewhere to the south of the Ohio River.” 

Before discussing the Chrysemys problem in Illinois it is well to 
eliminate those forms which do not occur within the state. Garman 
(1892) includes Chrysemys picta picta in his list of Illinois turtles, 
stating that it is “‘very rare, if it occurs at all.” It can be quite definitely 
stated at this time that this form does not occur in the state, and in the 


124 ILLINOIS BIOLOGICAL MONOGRAPHS 


PLate 16—The Chrysemys Problem: (Above)—A series of plastra of Chry- 
semys picta dorsalis, taken at Horseshoe Lake and vicinity, arranged to show 
variations in markings. The upper left specimen is typical of dorsalis. (Below)— 
Plastra of Chrysemys taken in one drag of a net at Meredosia on the IIinois 
River. The left-hand specimen is typical of marginata; the right-hand specimen 
is typical of bellit; the middle specimen is intermediate between the two. 


THE TURTLES OF ILLINOIS—CAHN 125 


present paper it is dropped from the state list. As to Chrysemys mar- 
ginata treleasei of Hurter, Bishop and Schmidt have shown that the 
red coloring of the plastron is due to a superficial deposit of red pigment, 
presumably an iron oxide, that similar deposits are to be found on other 
turtles of the same genus, and that there is no correlation whatever be- 
tween the presence of the red color and the geographic range of the 
turtles. They therefore reduce the original treleasei to synonomy with 
Chrysemys picta belli because of the approach to the typical belli in all 
matters other than the red coloring of the plastron which, being a super- 
ficial deposit, has no bearing on the case. Thus we find three subspecies 
of the genus Chrysemys occurring in Illinois: Chrysemys picta marginata, 
Chrysemys picta bellu, and Chrysemys picta dorsalis. The latter is re- 
ported in this paper for the first time in the state. 

Chrysemys picta marginata is an eastern form, extending from 
eastern New York westward through Indiana into eastern Ilinois. 
Chrysemys picta bellii is a western form whose range extends from the 
Rocky Mountains to western Illinois. In Illinois, therefore, the ranges 
of these two turtles meet and overlap, and over a great part of the state 
an intermediate form is found coincident with the overlap. In Indiana, 
typical marginata is found; in eastern Illinois typical marginata is also 
found, but along with it are found a number of turtles in which the nar- 
row dark plastral area shows a tendency to enlarge and creep out along 
the sutures, especially along the femoro-anal and gulo-humeral unions. 
In central Illinois, particularly in the region of the Hlinois River, this 
tendency for the plastral mark to enlarge and spread increases, and the 
size of that area becomes larger, tending toward the bellii characteristic. 
In a series of 212 turtles of the genus Chrysemys taken at Meredosia on 
the Illinois River, 12 specimens were typical marginata, 33 were typical 
belli, and the remaining 170 were intermediate between the two, extend- 
ing through every degree and variation of plastral markings. Of this 170, 
32 were more similar to marginata than to bellii, 46 were more similar 
to belli than to marginata, and the remaining 92 showed such intermedi- 
ate markings that it would be difficult to say which of the two forms they 
resembled unless one became arbitrary in the matter. These intermedi- 
ate forms are what Bishop and Schmidt call “intergrades.” 

Chrysemys picta dorsalis is a southern form, extending westward into 
Louisiana, Arkansas, and Texas, and northward into the extreme south- 
ern tip of Illinois. Thus it is seen that somewhere in the southwest 
the ranges of dorsalis and bellii meet, while the ranges of dorsalis and 
marginata meet, almost as indicated by Bishop and Schmidt, ‘‘somewhere 
to the south of the Ohio River.’’ From Cairo and Metropolis the writer 
has collected typical specimens of dorsalis, with the very characteristic 


126 ILLINOIS BIOLOGICAL MONOGRAPHS 


dorsal band and the immaculate plastron. He has also collected from 
southern Illinois and from the extreme western tip of Kentucky and 
northwestern Tennessee a full and complete set of forms entirely inter- 
mediate between dorsalis and bellii, both as to the development of the 
vertebral band and the development of the dark area on the plastron, 
with typical dorsalis and typical bellii at opposite ends of the series, and 
with marginata in the middle. (This series is shown in Pl. 16.) The 
question is, then: What are we going to do with these intermediate 
forms? What are we going to call them? 

If the plastral markings of marginata and bellii, and the lack of 
plastral markings of dorsalis, are definite genetic characters—as they 
appear to be since they are practically constant and consistent over the 
great range of the forms, then, where the ranges of the two subspecies 
meet and overlap, the intermediate forms found there may well be con- 
sidered as ybrids between them, hybrids showing incomplete dominance. 
This is on the understanding of a hybrid as being a cross between two 
distinct species or subspecies, or between individuals having distinctive 
differences, and without reference to any question of fecundity. In the 
eastern part of the country we find only marginata; in the western part 
only bellu. Where the ranges of these two overlap (Illinois) we find the 
hybrids, plus occasional typical examples of each, and we find the hybrids 
in far greater abundance than either of the parent stocks. The same is 
true where the range of southern dorsalis overlaps that of bellii and 
marginata. Since there is no physical barrier of any kind between 
marginata and bellii, or between dorsalis and either marginata or bellu 
in the area in which the hybrid forms occur, and since every possible 
variation exists between the typical parent forms within this area, it is not 
to be supposed that the hybrids comprise an additional subspecies. 

Since the primary distinction between marginata and bellii lies in the 
size and distribution of the dark plastral area, it is perhaps well to deline- 
ate as definitely as possible between the two subspecies. Bishop and 
Schmidt (1931) have reduced this matter to a mathematical basis com- 
paring the maximum width of the dark plastral figure to the width of 
the plastron as measured from the lateral margins of the abdominals 
where they meet the marginals in the bridge: 

Chrysemys picta marginata: 


Dark area occupies from 13 per cent to 67 per cent of the plastral width. 

Average: 36 per cent. (7 specimens out of 51 exceed 50 per cent.) 
Chrysemys picta belli: 

Dark area occupies from 56 per cent to 85 per cent of the plastral width. 

Average: 74 per cent. (5 specimens out of 44 fall below 70 per cent.) 
Chrysemys intergrades: 

Dark area occupies from 15 per cent to 78 per cent of the plastral width. 

Average: 55 per cent. 


THE TURTLES OF ILLINOIS—CAHN 127 


From the above figures it is seen that the hybrids extend through almost 
the entire range from minimum marginata to maximum belli. The writer 
has checked these figures on something over 600 turtles of the genus from 
within Illinois, and is quite in agreement with Bishop and Schmidt. 
Certain points, however, have been brought out by his study. 

Since Bishop and Schmidt have shown that out of 51 specimens of 
marginata only 7 exceeded 50 per cent, and out of 44 bellii only 5 fall 
below 70 per cent, I have quite arbitrarily taken 60 per cent (instead 
of their 55 per cent) as the dividing line, and say that any turtles be- 
tween 50 per cent and 60 per cent show “marginata tendencies,” while 
any between 70 per cent and 60 per cent show “‘bellii tendencies.” Other- 
wise, since the intergradation is so complete and is illustrated by such a 
great assortment of percentages, it would be quite impossible to designate 
which way the hybrids are tending. While I have taken typical marginata 
from many localities in southeastern Illinois, this form does not extend 
its range far into the state before the hybrid forms begin to appear, and 
these fall into the group showing 
definite marginata tendencies. 
Such hybrids from the upper Em- 
barrass, the Little Wabash, and 
the Upper Kaskaskia average 58 
per cent. On the other hand, 
turtles from the lower Illinois 
River and its tributaries show the 
bellii tendencies, averaging 66 per 
cent. There is a third series of 
localities, as the lower Sangamon 
and certain regions on the upper 
Illinois River, where the variation 
covers almost the entire range of 
the hybrid scale and one cannot 
definitely state which way the 
hybrids are tending: they are 
wholly intermediate. The accom- 
panying map illustrates the distri- 
bution of hybrid Chrysemys ac- 
cording to their “tendencies” in 
localities where twenty or more 
specimens were available for Bere ieee ae 
study. From this map one will : 
note that apparently the drainage 
basin of the Illinois River and its Map 12—Intermediate Chrysemys. 


ard marginata “ 
d bellii 5 


12 


oo 


ILLINOIS BIOLOGICAL MONOGRAPHS 


major tributaries is the zone of maximum transition between these two 
subspecies. While typical Chrysemys picta dorsalis has been taken in the 
extreme southern tip of Illinois, it is distinctly rare, and is associated 
with transition hybrid forms tending toward the marginata type. Similar 
specimens showing dorsalis tendencies have been taken southward to and 
including Reelfoot Lake, Tennessee, where, however, typical dorsalis is 
the abundant and dominant form found. 

The facts of the Chrysemys problem line up as follows: (1) The 
most striking difference between the three subspecies occurring in IIli- 
nois is the plastral marking. (2) In one part of the country we find 
one expression of plastral markings (marginata); in another part a 
second expression (belli) ; in a third part still another expression (dor- 
salis). In these areas the turtles breed typical expressions of the charac- 
ter. (3) Where these areas overlap (Illinois) we find turtles in which 
the character is expressed through a series of variations which show 
tendencies toward one or the other of the typical character expressions, 
or else so intermediate between the two as to give no indication as to 
which of the parent expressions they tend toward. (4) In these areas of 
overlapping, the number of individuals which exhibit the typical ex- 
pression of the character concerned is far less than the number of the 
individuals showing variations or intergradations. 

It seems to the present writer that there are two possible explanations 
that might be offered to account for these facts. Both of these are 
offered herewith merely tentatively, for the writer realizes fully that the 
only way in which the truth of the matter can eventually be ascertained 
is by careful and prolonged breeding experiments, a series which would 
require years to complete, and which he is in no position to undertake. 
(1) We are dealing with three distinct subspecies, marginata, bellu, and 
dorsalis, each being a separate form. Where the ranges of these touch 
and overlap, we have a hybridization between those whose ranges join, 
with all sorts of variations resulting. This would be termed “interspecific 
hybridization.” (2) We are dealing with but one single species or sub- 
species, in which we have three expressions of genetic characters. This 
might well be called “intraspecific hybridization.” 

This latter idea has not yet been expressed, so far as the writer 
knows, and a word further might be in order. If the plastral markings 
of the three typical subspecies are the result of the expression of different 
genetic complexes, the following facts would be true: (1) Within the 
limits of distribution of each subspecies, each subspecies would breed 
true. (2) Where the limits join or overlap we have a series of expres- 
sions which differ from either parent and do not resemble either exactly, 
which may show a tendency to resemble one of the parents. (3) The 
number of individuals showing the expression of variation between the 


THE TURTLES OF ILLINOIS—CAHN 129 


two parents will far outnumber those individuals which exactly resemble 
the parents. These facts (2 and 3) are illustrated in the area in which 
hybridization occurs. If marginata and belli and dorsalis are pure lines, 
where these pure lines come together in the overlapping range of what 
we are calling the typical subspecies, we would expect quantitative vari- 
ation between the pure lines. On the surface, at least, this seems to be 
true. 


Chrysemys picta marginata (Agassiz) 


(Painted turtle; red-legged turtle; mud turtle; pond turtle) 


Testudo cinerea Bonnaterre 1789 Chrysemys cinerea Boulenger 1889 
Enws cinerea Schweigger 1814 Chrysemys marginata marginata 
Emys picta Gravenhorst 1829 Stejneger & Barbour 1923 
Chrysemys picta (var. 2) Gray 1855 Chrysemys bellii marginata Ruthven 
Chrysemys marginata Agassiz 1857 1924 

Clemmys picta (var. 2) Strauch 1865 Chrysemys picta bellii Bishop and 
Chrysemys pulchra (part) Gray 1873 Schmidt 1931 


DescriIpTION.—Shell wide, depressed, broadest at about the eighth 
marginal scute; rather uniformly convex, highest in the middle. The 
posterior lateral marginals flaring. Surface smooth for the most part, 
but sometimes with weak concentric rugae near the lateral margins of the 
costal scutes and extending to the median margins of the contiguous 
marginals; unkeeled even in the young individuals. Vertebral scutes 
wider than long, and about equal to the costals in width. The anterior 
margin of the first vertebral greatly exceeding the posterior margin. 
Second, third, and fourth vertebrals hexagonal, the anterior and posterior 
margins of the second and third being approximately equal, while the 
anterior margin of the fourth is greater than its posterior margin. The 
fifth vertebral is somewhat the smallest of the series and tends to be 
pentagonal; in some specimens it shows a tendency to divide along the 
mid-dorsal line. The vertebrals alternate with the costals. Costal scutes 
somewhat larger than the vertebrals. The first costal.is trapezoidal, its 
maximum length and width being about equal. Second and third costals 
wider than long, the second being a trifle wider than the third but 
having nearly the same length. The fourth costal is the smallest of this 
series, and approaches a square in shape. The nuchal is long, narrow, and 
with a definite median notch anteriorly; this may or may not be bordered 
on each side by a series of serrations extending on to the adjacent 
marginals, and these serrations may be very small or highly conspicuous. 
The marginals number 24. Posteriorly the marginals begin to flare at 
about the seventh scute, and there is a slight caudal notch. The plastron 
is broad and flat, truncate anteriorly and posteriorly. Gulars finely ser- 
rated along the anterior margin and with the anterior lateral angle pro- 


longed into a blunt “tooth.” Interhumeral and interfemoral sutures usu- 


130 ILLINOIS BIOLOGICAL MONOGRAPHS 


ally about equal, and both a trifle shorter than the interpectoral suture. 
Pectoral scutes transverse, about half the length of the abdominals. 
Interanal suture about equalling the interabdominal suture. The bridge 
is wide, rising rapidly to the marginals. The inguinal is larger than the 
axillary element, and both are triangular. The head is moderate in size, 
and distinctly flattened dorsally. Upper jaw with a distinct median notch 


Pirate 17.—Chrysemys picta marginata: A, Adult, ventral view. B, Adult, 
dorsal view. C, Adult, lateral view. D, Newly hatched young, ventral view. E, 
Newly hatched young, dorsal view. F, Head study of an adult. 


5) 


THE TURTLES OF ILLINOIS—CAHN 131 


which is bordered on each side by a distinct “tooth.” Snout short, not 
projecting far; nostrils anterior, terminal, and close together. Alveolar 
ridge weak. Lower jaw but little upturned and with a small median 
tooth. Limbs well developed, the posterior the larger. Anterior limbs 
with rows of transverse imbricated scales; digits 5, claws 5, these being 
strong and curved. Hind limbs flattened and expanded; digits 5, claws 4, 
the fifth toe represented by a tough marginal projection and without a 
claw. Claws on the hind limbs shorter than on the fore. Hind feet large. 
All digits fully webbed to the base of the claws. 


CoLoraTION.—The general plan of the color pattern of Chrysemys 
picta marginata is quite stable, but the fine details prove to be highly 
variable. The carapace is dark olive green. A very narrow black- 
bordered red or yellowish line extends from the anterior margin of the 
nuchal to the notch of the caudals; in some cases this line is almost 
indistinguishable. The margins of the scutes are yellow, which clearly 
outlines each scute. The posterior margin of the costal and vertebral 
scutes is bordered by a narrow black line; the anterior border of these 
scutes shows a wider line of yellow (sometimes orange, sometimes ap- 
proaching red), lying against the preceding black line. Vertebrals and 
costals often with yellow or red lines, dots or blotches, these usually 
rimmed with black. Marginals with the dorsal surface decorated with 
lines and spots of yellow and bright red, usually tending toward a con- 
centric pattern around a brilliant red spot near the center of the lateral 
margin of the scute. This red spot is prolonged down the middle of the 
ventral surface of the marginals, forming a striking color contrast against 
the almost black background. The plastron is bright yellow or straw 
color, often covered with a superficial layer of brown or reddish deposit ; 
it bears a dusky or black-mottled central area extending from the pos- 
terior angle of the gulars to about the middle of the anals. This dark area 
shows no tendency to produce lateral branches along the sutures, especi- 
ally not along the gular-humeral articulation. The axillary and inguinal 
elements are largely black, blotched with bright red or orange-yellow. The 
distal margins of the pectorals and abdominals, which form the bridge, 
are bordered with black. The more conspicuous of the head and neck 
markings, all of which show much variation, are usually as follows: On 
each occipital region is a large yellow blotch, nearly the size of the eye, 
prolonged backward as a narrower yellow line along the neck; a short, 
wide dash behind the eye often connects with the previously mentioned 
spot; a stripe extends from the mid-ventral margin of the orbit down- 
ward and backward along the anterior ventral margin of the tympanum, 
where it meets a short line from the lateral angle of the lower jaw, and 
together they run as a conspicuous ventro-lateral line down the neck; 
a short median yellow line begins at the “tooth” of the lower jaw, but 


132 ILLINOIS BIOLOGICAL MONOGRAPHS 


bifurcates to extend down the neck. Between these major lines are 
many fine lines of yellow. The top of the head is usually mottled, and 
shows a median line from the nostrils to a point just behind the eyes. 
The iris is golden brown. Two bright red stripes on the anterior surface 
of the fore limbs, and three on the under surface of the hind limbs. Tail 
with yellow or orange stripes. Other soft parts mottled with red and 
yellow. 

Younc.—The newly hatched young are readily recognizable by their 
resemblance in general form and coloration to the adult. However, the 
head, instead of being flat dorsally, is convex and highly domed above. 
The snout is very short; eyes large in proportion to the head. The cara- 
pace is nearly circular in outline and very flat and without a keel. Nuchal 
scute nearly square, the anterior median notch usually not visible. The 
mid-dorsal stripe is quite clear but is always very narrow, being merely a 
line. The plastral markings are almost solid black, but of the same shape 
and form as in the adult. 


Sex DIFFERENTIATION.—The sexes may be distinguished externally 
by the fact that in the male the claws of the front feet are long, slender, 
and curved; those of the female are short and stout and but slightly 
curved. The vent of the male lies beyond the margin of the carapace, 
of the female, beneath it. The females are larger than the males when 
fully developed. 


GrocrapHic DistriputTion.—The recent work of Bishop and Schmidt 
(1931) on the genus Chrysemys enables us to outline the geographic 
distribution of the various species of the genus with greater clarity than 
was possible some years ago. Chrysemys picta marginata occurs through- 
out the great territory of eastern United States, extending from eastern 
New York westward through western Pennsylvania, Ohio, Indiana, 
southern Michigan, and into eastern Illinois and Wisconsin. The northern 
and southern limits are very uncertain due to the confusion of names 
existing in the literature and cannot be accurately defined until a great 
deal of field work has been done. As an example, Chrysemys picta is re- 
ported as abundant over the province of Ontario by Nash (1906), and 
no mention is made of marginata, which is probably what he has called 
picta over most of that region. It is not mentioned as an inhabitant of 
New England by Babcock (1919). Surface (1908) quotes marginata from 
several localities in northwestern Pennsylvania, and incidentally says 
that “intergrading forms [between picta and marginata| are rather com- 
mon,” a reference to this matter which Bishop and Schmidt have ap- 
parently overlooked. Morse (1904) reports it as one of the commonest 
turtles in Ohio, and it is reported by Ruthven (1912) from the southern 
half of lower Michigan. Hay (1892) reports it as “everywhere” in 
Indiana, and gives its range as the “northern states of the Mississippi 


THE TURTLES OF ILLINOIS—CAHN 133 


Valley from Ohio to Kansas and north to Lake Superior’’—which is 
both too much and not enough! When we come to Wisconsin, we find 
Pope and Dickinson (1928) reporting marginata as “statewide,” with 
records from the extreme north to the extreme south, and as far west as 
Grant County on the Mississippi; Hoy (1883) gives it as “abundant 
everywhere,” while Higley (1889) reports it as very common; Cahn 
(1929) has typical specimens from southeastern Wisconsin, but failed to 
distinguish the hybrid forms. Since Wisconsin, or part of it at least, lies 
in the area of overlap of ranges, it is in need of a thorough going over. 


Ittino1s Recorps.—When we come to Illinois, it is very difficult to 
know what to do with the published records which cannot be verified 
by a re-examination of the original material. Since most of the writers 
did not recognize the hybridization between marginata and belli it is 
extremely difficult to determine just what they were dealing with. We 
can guess at probabilities, but prefer not to do so. Yarrow (1882) re- 
ports marginata from Mt. Carmel. Garman (1892) records it “through- 
out the state; common... .” with records from Lake County, 
Nippersink Lake, Oregon, Nor- 
mal, Peoria, Phillipstown and Mt. 
Carmel; Garman (1888) says that 
it does not occur in the Missis- 
sippi bottoms near Quincy, which 
statement is quite correct. Davis 
and Rice (1883) do not list mar- 
ginata at all from Illinois, but re- 
cord picta as ‘abundant through- 
out the state,” which is quite in- 
correct. Hankinson (1917) is 
quite frank about his Chrysemys 
around Charleston, calling them 
“Chrysemys (species?),”” though 
he probably had mostly marginata 
with some hybrids as well. Bishop 
and Schmidt (1931) report pure 
marginata from southeastern I[lli- 
nois, but cite no localities. The 
writer has examined specimens 
unquestionably Chrysemys  picta 
marginata from the following IIli- 
nois localities: Paradise Lake at 
Mattoon, Urbana, Rockford, Ha- 
vana, Danville, Arlington Heights, 
Fox Lake, Robinson, Meredosia, Map 13.—Chrysemys picta marginata. 


134 ILLINOIS BIOLOGICAL MONOGRAPHS 


Lawrenceville, Mt. Carmel, Carmi, Louisville, Shawneetown, Harris- 
burg, Shelbyville, Sims, Metropolis, Effingham, Kankakee, Elizabeth- 
town, Paris, Greenup, and Newton. In preparing the map of distribu- 
tion of the form, only the above localities where typical marginata were 
examined have been listed. It must be borne in mind, also, that at some 
localities, as Meredosia, Havana, etc., as well as in the northern counties, 
hybrids were also present. 


Hasitat.—Chrysemys picta marginata is a common inhabitant of the 
smaller lakes, ditches, temporary ponds, and sluggish waters of the 
eastern and southeastern portion of the state. Its habitat preference is 
distinctly for shallow, soft-bottomed, weedy lakes, and it distinctly 
avoids fast water and both rocky and gravelly environments. Almost any 
muddy ditch or the backwater of a stream or river is likely to have its 
population of this turtle in surprising numbers. It is associated almost 
always with an abundant growth of aquatic vegetation, and often the 
carapace is found to be overgrown with masses of algae. Whether it 
is the vegetation or the soft bottom accompanying vegetation which is the 
major attraction would be hard to say, but the combination, usually in- 
separable, affords the turtle the abundance of food and highly adequate 
protection in which it finds its optimum environmental requirements. 
Masses of Vallisneria, Potamogeton, Elodea, and the intertwining nets 
of algae are likely to shelter great numbers of these turtles. 


Hasits.—There is considerable diversity of individual habits exhibited 
among these turtles, some being highly aquatic, others showing a tendency 
toward a terrestrial habit. During the summer and fall in particular I 
have frequently found specimens wandering about in fields and woods 
nearly half a mile from water, their wanderings having no connection 
with age, sex, breeding, or hibernation. Such land-journeying specimens 
are distinctly less timid than the more aquatic ones and, while they mildly 
resent being disturbed, they quickly recover their equanimity and pro- 
ceed with their wanderings. Those turtles which show aquatic prefer- 
ences are very wary and difficult to approach. They spend hours floating 
at the surface of the water, the head protruding while the body lies 
partially concealed by the protecting bed of vegetation which they dare 
not forsake. At the first sign of danger they disappear amid a tiny swirl 
caused by the sudden action of the hind legs, and are very slow and 
cautious about again venturing to the surface. As a whole, the species 
enjoys basking in the sunshine, and the turtles may be seen lined up on 
partially submerged logs or along the sloping banks of the pond, lazily 
absorbing the warmth. They lie with their hind legs fully outstretched 
and entirely relaxed, and with the eyes closed they give the observer the 
impression of sleeping. But notwithstanding their complete relaxation, 
the least approach of danger startles them into activity, and they plunge 


THE TURTLES OF ILLINOIS—CAHN 135 


from their log or scramble down the bank into the water where they 
bury themselves in the mud at the bottom. Their return to the basking 
place is slow and cautious, and they do not emerge until the neighborhood 
has been carefully scanned and inspected. 

As swimmers they are fast and powerful when speed is necessary, 
the flattened hind limbs and the wide webbing of the digits giving them 
excellent organs of propulsion. When not frightened, however, they 
walk slowly and cautiously along the bottom, peering to the right and 
left among the dense vegetation in search of possible food. Again, they 
may lie for a long period entirely motionless on the bottom, the legs half 
drawn up, the head just protruding beyond the shell, resting. 

When disturbed and handled, the turtles snap vigorously for a time 
and then seem to take a philosophical attitude and make the best of the 
situation. Their bite is quite harmless due to the weakness of the jaws, 
but they are fast in their actions and sure of their aim. In captivity 
they quickly adjust themselves to their surroundings and in a few days 
will begin to eat and behave naturally. They can be kept for months or 
years in a suitable aquarium; they become very tame and eat from the 
hand within a few weeks after capture. 

As the summer wears on and the chill of autumn pervades the air, 
they become more and more sluggish in their reactions and finally for- 
sake entirely their basking activities. After mid-October, unless the 
weather conditions are unusual, they are not seen at the surface, and 
hibernation begins at about this time. They hibernate in the mud at the 
bottom of the pond, or in the runways of muskrat burrows, or in “‘cave- 
ins” along the bank. In the southern portion of the state the hibernation 
is less marked, and even in the vicinity of Danville the turtles may some- 
times be seen crawling slowly and sluggishly along on the bottom during 
the winter. They reappear shortly after the ice goes out and by mid-April 
their heads are to be seen poking above the surface, though they do not 
come out to bask until the air has warmed up to a considerable degree. 


BREEDING Hapits.—Long before the nesting season begins, the turtles 
become increasingly active, often traveling in pairs, with the male follow- 
ing or chasing the female. Sometimes two or even more males are to be 
seen thus occupied pursuing a single female; always it is the female that 
is in the lead. On one occasion I saw the male catch up with the female; 
he climbed on top of her carapace and seemed to be clawing at her head 
and neck. However, she quickly evaded him, and when last seen he was 
again in pursuit. No notes on copulation are available. The nesting habits 
of the turtles of the genus Chrysemys have been described by Babcock 
(1919) who quotes observations of Thoreau and others relative to picta, 
while Stromsten (1910) describes the process for belli, That marginata 
is similar to these, the following transcription from my field notes will 


136 ILLINOIS BIOLOGICAL MONOGRAPHS 


bear out. (In one respect at least, the turtles of the genus Chrysemys 
differ from other species found in the state: they lay in the late after- 
noon and early evening instead of in the early morning. Thus it happens 
that the turtle described herewith is a bit unusual only in that it was 
found digging its nest at 4:10 in the afternoon; it is usually done later.) 
“The nest was in compact, black soil along the edge of a road, within 
fifteen feet of a vegetation-choked pond from which her tracks led 
straight to the point where she was at work. When discovered, the turtle 
had dug a hole about half an inch deep. She paused for a few minutes, 
standing motionless while I sat down a yard away, watched me closely, 
then resumed her digging and paid me no further attention during the 
process, though I moved considerably in order to watch the performance. 
Her front feet were firmly planted and were not moved from their po- 
sition; the digging was done entirely with the hind feet. She scratched 
several times with one foot; then cupping the foot by drawing the digits 
together, she carefully scooped the loosened dirt out of the hole and 
deposited it on the opposite side of the hole behind her. This was then 
repeated with the opposite foot. As each load was removed, she dis- 
charged a stream of water through the cloacal apperture directly into the 
hole, softening the dirt prior to the scratching that followed. She worked 
briskly and without pause, one foot after the other removing a pinch of 
dirt to the growing pile behind her. When she had dug down about two 
inches, the bottom of the hole was very muddy; from then on no more 
water was discharged, and this mud was dug out and pushed back. At 
three and a quarter inches (subsequent measurement) she began to 
enlarge the bottom of the hole a bit, making a sort of oval chamber, the 
longer axis parallel with her position. The digging that was watched 
required sixty-four minutes to complete; then the first egg was laid. In 
laying, she pulled her head entirely within the shell and, apparently with- 
out any effort, deposited the egg in the hole, reaching in with the right 
hind leg to shove the egg over to one side and to lay it horizontally. The 
seven eggs that followed were laid at intervals of about one minute, and 
each was rearranged with the right hind foot after laying. The eighth 
egg deposited, she remained motionless for about three minutes, then 
began to fill in the hole. She reached back with one leg after the other 
and raked small quantities of dirt into the hole, tamping it down with the 
sole of the foot and occasionally discharging water on it and then tamp- 
ing it down still more. With the hole almost filled, she seemed to switch 
trom the sole of the foot to the dorsal surface, kneading the dirt into 
place instead of tamping it down. When the hole was completely filled 
she watered the spot thoroughly, then repeatedly drew the flat surface of 
the plastron over it, smoothing the surface. Finally, the front feet still 
in position, she reached out and drew over the nest an accumulation of 


THE TURTLES.OF ILLINOIS—CAHN 137 


débris, leaves, twigs, dead grass, etc., concealing the last trace of the 
disturbance. Without looking around to inspect her work, she headed for 
the pond and disappeared.” The entire process under observation re- 
quired an hour and fifty-two minutes. Regarding the age at which 
Chrysemys breeds, Agassiz (1857) says that picta does not breed until 
its eleventh summer. 

Eccs.—The number of eggs varies from four to ten, with six or 
seven being the average number deposited. When laid, the eggs are 
translucent and almost flesh-colored, but as the shell dries out it becomes 
pure white, opaque and rather brittle. The measurements (in millimeters ) 
of the eight eggs in the set dug from the nest described above are as 
follows: 30x18, 31x17, 30x17, 30x17, 30x18, 31x18, 31x17, 30x 
18; average: 30.3 x 17.6. There is no information available to the writer 
regarding the incubation period, but young turtles, evidently but newly 
hatched, have been taken in late August and early September as well as 
in late June, which inclines the writer to agree with Newman’s suggestion 
(1906) that “forced hibernation of embryos” results when turtles lay 
late in the season. In spite of the careful effort of the turtle to hide her 
nesting site, the eggs are very frequently dug up by skunks and raccoons, 
both of which are experts at discovering these choice delicacies. 

A recent note by Wilcox (1933) on the incubation period of the 
painted turtle (presumably Chrysemys picta picta) in New York, is of 
interest. On June 26 he observed a female digging her nest; on Septem- 
ber 8, Wilcox dug down to the nest and found the young turtles just 
coming out of the shell. They measured almost exactly one inch in 
length. This gives an incubation period of nine and a half weeks. 
Nichols (1933) remarks that the above brood was probably unusually 
advanced for the region and reports eggs laid on July 17, 1925, hatched 
April 3, 1926, and eggs laid June 25, 1928, hatched October 28 of the 
same year, 

Foop Hasirs.—Hay (1893) reports the food of marginata as being 
“insects, tadpoles and other feeble and small animals.” An examination 
of ten stomachs from specimens from southeastern Illinois leads the 
writer to make the statement that they are omnivorous, with a strong 
tendency toward vegetarianism. These stomachs showed the remains of 
aquatic larvae such as Chironomous and other dipterous forms, nymphs 
of dragonflies, mayflies and stoneflies, aquatic beetles, gastropods, finger- 
nail shells, small crayfish, tadpoles, ants, flies, and honey bees; only one 
small, unidentifiable minnow was found. Vegetable matter predominated, 
being in the form of chewed-up masses of aquatic plants, algae, rootlets, 
leaves, stems, and grass. Three specimens showed evidence of the 
Scavenger habit; there is no question of the fact that if dead matter is 


138 ILLINOIS BIOLOGICAL MONOGRAPHS 


available, this turtle shows well developed scavenger instincts. When 
eating anything too large to be swallowed entire, the morsel is held firmly 
in the mouth and is then ripped to tatters by the claws of the front feet, 
these feet acting either separately or together. 

Economic ImMportaNcE.—In spite of the abundance of turtles of this 
genus everywhere throughout the state, their small size makes them un- 
desirable for human consumption, in spite of the fact that the flesh is 
firm and of excellent flavor. Their scavenger habit makes them a 
valuable asset in the destruction of animal matter. While they do not 
ordinarily destroy living fish or fish eggs, it is conceivable that in such 
places as fish breeding pens these turtles might be a serious annoyance 
and cause considerable loss. 


TABLE 12.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Chrysemys picta marginata 
(Measurements in millimeters; weight in grams) 


Carapace Plastron Tail 
Speamen - Head |———————__ Weight Sex 
Length} Width | Length | Width | Depth Total A-T 
Wl sieBincge safeties 162 116 148 93 58 24 57 42 484 io) 
a epee yao 143 110 133 88 Ny De 45 40 321 i) 
Sire os ici syncs BXees 138 101 129 81 50 22 47 39 368 ) 
Dh erayaxsrete ncciaveere 133 103 125 81 52 21 40 38 363 g 
sD ohiretace Atha re tome 133 98 120 81 43 20 45 39 283 ou 
Oh Aa ara atone 133 98 a yf 77 43 20 51 32 308 oy 
Toate eetaiian cemteiiens 125 94 116 77 45 19 44 39 266 ie) 
Sisatretar eave eae toes 123 96 ith WG} 76 43 18 50 37 254 ex 
Oita ral cheVakeryeatar ots 122 90 pin hi 70 38 18 55 40 241 fo 
LO ieiissiesiaee os 118 85 102 tps REI i1Y/ 50 35 176 fof 
ab enema cecdc as 115 87 106 68 42 18 35 32 213 iP) 
A Dis cs 5 dteicveve: veretove 82 68 75 65 32 14 44 35 96 fol 
US iteeertoeny arses 30 28 28 21 13 8 16 14 o 
5 eran eracr 27 27 26 20 lal 7 12 11 5 


Chrysemys picta bellii (Gray) 


(Western painted turtle; red-legged turtle; mud turtle; pond turtle) 


Emys belli Gray 1831 Chrysemys pulchra (part) Gray 1873 
Emys oregoniensis Harlan 1837 Chrysemys belliit True 1883 
Chrysemys oregoniensis Holbrook 1842 Chrysemys cinerea bellii Boulenger 1889 
Chrysemys bellii Gray 1855 Chrysemys marginata bellii Stejneger & 
Chrysemys nuttalii Agassiz 1857 Barbour 1917 
Clemmys oregoniensis Strauch 1862 Chrysemys bellii belli Ruthven 1924 
Chrysemys picta (part) Gray 1863 Chrysemys picta belli Bishop and 
Clemmys picta (var. b and c) Strauch Schmidt 1931 

1865 


DescripTion.—Shell broadly ovate, widest posteriorly ; depressed and 
unkeeled ; uniformly convex. The posterior lateral marginals flaring. Sur- 
face smooth except for occasional longitudinal rugae near the lateral 
margin of the costal scutes, and extending onto the median of the 


THE TURTLES OF ILLINOIS—CAHN 139 


marginals. Costal scutes alternating with the vertebrals. Anterior mar- 
gin of the first vertebral approximately twice the length of the posterior 
margin and about a quarter greater than the length of the scute. Second 
and third vertebrals almost equal in size as well as in width; hexagonal ; 
the anterior and posterior borders about equal to the length of the scute. 
Fourth vertebral wider than long in most of the specimens, and also 
hexagonal. Fifth vertebral somewhat smaller than the fourth. Costal 
scutes large, about equalling the width of the vertebrals. First costal 
trapezoidal, its length and width about equal. Second and third costals 
wider than long, tending toward rectangular in shape, the third smaller 
than the second. Fourth costal the smallest of the series, almost square. 
Nuchal scute elongate but quite wide in most specimens—usually wider 
than in marginata; its anterior margin is usually weakly serrated and the 
serrations more often than not do not extend to the adjacent marginals. 
Marginals number 24, with a shallow caudal notch. The marginals follow 
the slope of the carapace up to the seventh scute, from which region they 
begin to flare. The plastron is broad and flat and is truncate both anter- 
iorly and posteriorly, the anterior margin finely serrated. Gulars tri- 
angular, their anterior lateral angle protruded forward into a weak, blunt 
“tooth.” Interhumeral and interfemoral sutures approximately equal, 
and the shortest of the median articulations. The interpectoral suture 
only a trifle longer than either of the preceding sutures. Pectoral scutes 
transverse, about half the length to the abdominals, which are by far the 
largest of the plastral elements. Anals large, triangular, the interanal 
suture but slightly shorter than the interabdominal. The bridge is wide 
and strong. Inguinal scute larger than the axillary, both irregular in 
shape. Head moderate and distinctly flat on the dorsal surface and 
covered with plain, tightly drawn skin. Snout short, not projecting ; 
nostrils anterior, terminal, and set close together. Upper jaw with a 
distinct median notch which is bordered on each side by a short but 
definite tooth. The alveolar ridge is weak and poorly developed. Lower 
jaw only slightly upturned and with a median point which fits into the 
median notch of the upper jaw. Limbs strong and well developed, 
especially the posterior pair. Front legs with rows of transverse imbri- 
cated scales; digits 5, claws 5. Hind limbs flattened and expanded; 
digits 5, claws 4, the claw absent on the fifth (posterior) digit. Claws 
strong, pointed, curved. Toes fully webbed to the base of the claws. 
Tail slender and attenuated. 


CoLoration.—The carapace is dark olive green, each scute with a 
narrow buff margin along its anterior articulation. Other than this, the 
markings are extremely variable. There is a tendency for each costal 
scute to show evidence of a diagonal line of buff, or a few irregular 
transverse lines of red or yellow, and occasionally a few dots. There 


140 ILLINOIS BIOLOGICAL MONOGRAPHS 


is a very narrow mid-vertebral streak of buff or red, often, however, very 
inconspicuous or almost wanting. The marginals tend to have three 
transverse streaks, the outer two small and inconspicuous and often buff 


B, Adult, dorsal 
D, Newly hatched young, ventral view. E, Head 


PLate 18—Chrysemys picta bellii: A, Adult, ventral view. 


view. C, Adult, lateral view. 
study of an adult. 


THE TURTLES OF ILLINOIS—CAHN 141 


in color, the central one reaching to the lateral margin and blood red in 
color, terminating in a more or less distinct blotch. Ventrally this red 
spot is continuous with a brilliant red band, and the marginal scute shows 
streaks or blotches of buff and red on each side of this band. The bridge 
is traversed longitudinally by bars, lines, or blotches of red, orange, 
or buff on a dark olive background, these markings extending over the 
inguinal and axillary scutes. Inguinal usually with a blood red spot at its 
posterior lateral angle. The plastron is yellow, sometimes overcast with 
a brownish or reddish superficial deposit. The central region is marbled 
with black in a complicated, lyriform, bilateral design. This figure flows 
out along the sutures and occupies upward of 60 per cent of the area of 
the plastron. There usually is a clear, longitudinal area within this 
design, following the mid-ventral suture. The coloration of the fleshy 
parts is elaborate. The head and neck are striped with blood red and 
lemon yellow as follows: a yellow stripe from below the nostril to the 
posterior end of the jaw; two yellow stripes, joined at the nostril, pass 
through the orbit and terminate dorsal and ventral to the tympanum. 
Three orange or yellow stripes run along the neck, one starting at the 
tympanus, one at the corner of the mouth, and one on the occiput. On 
the ventral surface, a bifurcating yellow stripe starts at the symphysis 
of the lower jaw and extends back to the body, with a third stripe be- 
tween these two. Besides these major stripes, many fine yellow longi- 
tudinal lines cover the sides and ventral surface of the head and neck. 
The anterior surface of the fore limbs show two, three, or four broken 
lines, red on the limb and tending to yellow on each digit; the webbing 
tends toward a greenish yellow. The posterior limb usually shows three 
broken red or orange bands, the median the most conspicuous; this one 
extends onward to the ventral tip of the tail where it unites with its 
mate from the opposite side. The tail also shows two red lines dorsally 
which become yellow posteriorly as they unite to extend as a single 
stripe to the tip of the tail. The vent is usually set in a red spot. 

Younc.—The young show all of the typical markings of the adult, 
and, so far as the writer can determine, the markings on the plastron, 
though blacker and more solid than in the adult, yet retain the same out- 
line and relative proportion throughout life. The young are much more 
round than the adult, being almost circular in outline. The head is domed 
above and the eyes are large in proportion to the size of the head. There 
is never a trace of a keel in the young. The vertebral streak is perhaps 
a bit more clear in young individuals, but it is always very narrow, a 
mere line. 

Sex DIFFERENTIATION.—The sexes may be determined externally by 
the long claws on the front feet of the male, these being three or four 
times the length of the claws on the hind foot. They are slender and 


142 ILLINOIS BIOLOGICAL MONOGRAPHS 


curved. In the male the vent lies beyond the margin of the carapace. 
Fully grown females are larger than fully grown males. 


GrocRAPHIC DistRiBUTION.—Chrysemys picta bellii is a western 
painted turtle, with a range extending from the Cascade Mountains east- 
ward to the Mississippi River. Storer (1932) gives the status of the 
species in the far west as follows: “There is thus no definite basis for 
ascribing Chrysemys picta bellii to the region west of the Cascade 
Mountains. It is a species of the interior, definitely recorded from the 
Mississippi drainage, Colorado (New Mexico?), and eastern Washing- 
ton. Like many other vertebrates it evidently circles the northern margin 
of the Great Basin to reach its limit of range east of the Cascade system.” 
From these mountains, then, the range extends eastward. Blanchard 
(1922) records it from northwestern Iowa, where he found it to be 
abundant, and records its breeding. Strecker (1915) reports it from El 
Paso, Texas. For South Dakota it is reported to be common by Over 
(1923); Burt and Burt (1929) report it from Nebraska and from 
Colorado; Burt (1927) records it from eastern Kansas. From Missouri, 
Hurter (1911) records it for the entire width of the state, and Agassiz 
(1857) mentions its occurrence at Osage River and St. Louis. Crossing 
the Mississippi, we are a bit in doubt as to whether all the records of 
belli deal with this form or with the hybrids, since the eastern limits of 
the range north of Illinois have not been definitely worked out. Be that 
as it may, it is reported from Wisconsin by Pope and Dickinson (1928) 
as “state-wide” in distribution, and by Pearse (1923), who remarks that 
Chrysemys belli and C. cinerea appear to intergrade in the Madison 
region, “but a majority of the individuals resemble the former.’’ Bishop 
and Schmidt (1931) record it only from northwestern Wisconsin. In 
Michigan it is reported only from the western portion of the northern 
peninsula by Ruthven (1912). In Canada it is recorded for the Lake 
Nipigon region by Logier (1928). In discussing the distribution of this 
turtle, Bishop and Schmidt say: “This extension of what is in the main 
a plains species through the heavily forested area of Wisconsin, Mich- 
igan and Ontario seems explainable in part by the highway for dispersal 
supplied by the valley of the St. Croix and by Lake Superior itself.” 

Ittrnors Recorps.—Here again we have difficulty in sorting out what 
we may consider records of typical belli. Hurter (1911) records it from 
Randolph, Monroe, St. Clair, Madison, and Adams counties, all on the 
Mississippi River, which records are entirely correct. Davis and Rice 
(1883) do not mention it, but record picta as throughout the state, which 
is certainly entirely incorrect. Garman (1889) reports it from the Quincy 
region as “rather common in the sloughs, but not seen elsewhere,” which 
is correct. Again in 1892 he reports it from Quincy as very common, 
in the bottom-lands, but not taken elsewhere in the state. In his inter- 


THE TURTLES OF ILLINOIS—CAHN 143 


mediate report (1890) he says it 
is “.... closely related to C. 
marginata, but I have not seen in 
many hundred painted turtles ex- 
amined during eight years’ collect- 
ing, an intermediate example.” 


The writer has examined typical 
specimens from the following 
Illinois localities: Meredosia, 
Mattoon, Quincy, Peoria, Havana, 
Clinton, Hardin, Carlinville, the 
region directly across the Missis- 
sippi River from Burlington, 
Iowa, Beardstown, Rock Island, 
Murphysboro, Grafton, Lewiston, 
Geneseo, and Senachwine Lake in 
Putnam County. 


Hasirat.—Chrysemys  picta 
bellu shows a decided prefer- 
ence for the sloughs and_ shal- 
low backwaters of rivers. It is 
associated with shallow water, 
usually of a warm temperature, as 


well as with soft bottom and an Map 14—Chrysemys picta bellii. 
abundance of vegetation. In Illi- 

nois, at least, it seems to prefer ponds to rivers, and generally avoids 
current. 


Hapits.—Its habits are so similar in detail to those reported for the 
preceding species that it would be largely repetition to reprint them here, 
and the reader is referred to this section under Chrysemys  picta 
marginata. 

Nestinc Hasitrs.—The nesting of bellii has been well described by 
Stromsten (1910). Field notes made while watching the nesting of 
this turtle at Meredosia in 1931 check almost exactly with this published 
description, and since they are so similar to those reported for marginata, 
it seems unnecessary to repeat them. Like marginata, bellii digs with the 
hind legs while the front feet are fixed in position; it applies copious 
water from the cloaca to the material to be dug from the hole, and 
finally, during the laying of the eggs, it uses the hind foot to arrange 
the eggs in position within the nest. 


Eccs.—The number of eggs laid varies from four to ten, with six or 
seven being the normal number. When laid the eggs are flesh color and 


144 ILLINOIS BIOLOGICAL MONOGRAPHS 


translucent, and the shell dries white and opaque. A typical set of eggs 
measures as follows (in millimeters): 36x 18, 35x 18, 36x18, 36x 18, 
34x 18, 34x17, 34x 18, 34x 18; the average size of 41 eggs composing 
seven complements is 34.7x 17.8. They tend apparently to be a trifle 
larger than those laid by marginata. The young usually hatch in August 
or early September, but newly hatched individuals in June indicate 
again the possibility of embryonic hibernation. 


GrowtH.—The only recent paper dealing with the growth of any of 
our common turtles is that of Pearse (1923), who worked on Chrysemys 
at Madison, Wisconsin. Pearse recognized the “intergrade” condition of 
the Chrysemys of that region and says that the Madison turtles resemble 
belli more than marginata. Therefore, while he was probably studying 
largely hybrid turtles, his results are interesting and probably approxi- 
mate very closely the condition in either pure bellii or marginata. He 
captured his turtles, measured and tagged them, and turned them back 
to be recaptured at a later date. Table 13 is taken directly from his 
paper. His conclusions, based on this table are that “‘a turtle nearly 
doubles its length and weight during the second year of its life. After 
twelve years it would be about 135 mm long, and the growth rate would 
have decreased to about one-thirtieth of that during the first two years. 
An ordinary adult turtle measuring 150 mm in length is, using the data 
here presented as a basis for computation, about twenty-five years of 
age.” Unfortunately, Pearse does not state clearly what his criterion 
for age determination of turtles is; nor does Agassiz (1857) make it 
much clearer when he deals with picta and records its age-length relation- 
ship as follows: Ist year 26.5 mm; 2nd year 42 mm; 3rd year 51 mm; 
4th year 54 mm; 5th year 59 mm; 6th year 66 mm; 7th year 72 mm; 
8th year 74 mm; 9th year 77 mm; 10th year 80 mm; 13th year 92 mm; 


TABLE 13.—GROWTH OF TURTLES OF DIFFERENT LENGTHS 


Estimated 
Av. rate of : 
Length No. of growth: Estimated gs Wie Percentage 
mm records mm, per av. weight: INCrEASE: increase 
. yen grams gms. per 
year 

4025 eee eee eee ) 32.7 19 13.8 73.0 
50-60... 10 17.0 36 ulibea 31.0 
60=/0 bse. seycnsen as 12 16.7 50 12.7 25.0 
WO=80 28 secu ce ae 8 19.0 68 15.9 25.0 
SO=90 Nae senate. 3 4.2 106 Se2 5.0 
OOOO esa oerccces cre 11 6.0 134 Sito: 6.0 
LOQEIL O vercieterseasecce ane 13 3.5 170 Sal 3.3 
VWUOH120 so eiecce ces a 8 3.1 233 (ys) Ded. 
120-130); en sche oe 6 4.2 243 8.2 3.4 
1302140. goes ar 8 165 310 3.4 2.4 
T4O=1 50) ii fenaneent oe 6 1.6 362 3.9 Dheff 


THE TURTLES OF ILLINOIS—CAHN 145 


24th year 121 mm. Agassiz further reports for Chrysemys picta that “up 
to their seventh year the ovary contains only eggs of very small size, not 
distinguishable into sets; but that with every succeeding year there ap- 
pears in that organ a larger and larger set of eggs, each set made up of 
the usual average number of eggs which this species lays, so that speci- 
mens eleven years old, for the first time, contain mature eggs, ready to 
be laid in the spring.’ He further reports that fecundation occurs in 
the fall prior to hibernation, and that the act is repeated in the spring, 
starting with the seventh year of the turtle’s life. Just what the signifi- 
cance of this is has never been determined, but Agassiz believes that 
“fecundation does not appear to be an instantaneous act, resulting from 
one successful connection of the sexes, as it is with most animals. The 
facts related above show, on the contrary, that, in turtles, a repetition 
of the act, twice every year, for four successive years, is necessary to 
determine the final development of a new individual... .” There are 
some very interesting and somewhat difficult research problems involved 
in these ideas of Professor Agassiz! To these facts the writer would 
add that females from Paradise Lake at Mattoon measuring 106 mm in 
length contained tiny embryonic eggs while females 160 mm long con- 
tained at the same time eggs about to be laid. 


TABLE 14.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Chrysemys picta bellit 
(Measurements in millimeters; weight in grams) 


Carapace Plastron Tail 

pees Head |————————| Weight | Sex 

: Length | Width | Length | Width | Depth Total | A-T 

179 133 166 115 63 26 55 45 720 9 
160 115 148 102 59 24 48 40 540 Q 
158 121 146 98 51 23 49 39 510 9 
145 115 142 04 52 21 50 40 429 Q 
114 103 130 87 44 22 60 41 359 a 
113 72 107 94 36 18 a pe 187 o 


Chrysemys picta dorsalis (Agassiz) 
(Southern painted turtle; red-legged turtle; mud turtle; pond turtle) 


Chrysemys dorsalis Agassiz 1857 

Chrysemys picta (part) Gray 1863 

Clemmys picta (var. d) Strauch 1865 

Chrysemvys cinerea dorsalis Boulenger 1889 

Clemmys cinerea (part) Strauch 1890 

Chrysemys marginata dorsalis Stejneger and Barbour 1923 
Chrysemys picta dorsalis Bishop and Schmidt 1931 


146 ILLINOIS BIOLOGICAL MONOGRAPHS 


PLaTE 19.—Chrysemys picta dorsalis: A, Adult, ventral view. B, Adult, dorsal 
view. C, Adult, lateral view. D, Newly hatched young, dorsal view. FE, Newly 
hatched young, photographed to bring out the granular surface of the scutes. F, 
Head study of an adult. 


THE TURTLES OF ILLINOIS—CAHN 147 


DescripTION.—Shell elliptical in outline, occasionally tending toward 
broadly oval; depressed and without a trace of a dorsal keel. The outline 
of the shell tends to be wider than in either marginata or belli, and to be 
slightly less depressed. Marginals flaring posterior laterally, the curvature 
of the rest of the shell being gradual and uniform. The vertebral series 
of scutes is very wide, much wider than in either marginata or belli, the 
width of these scales considerably exceeding the width of the costal 
scutes. First vertebral trapezoidal, about the length of the second, but 
distinctly narrower; its anterior margin greatly exceeds its posterior 
margin. Second, third, and fourth vertebrals broader than long, and 
broader than the costals, with the anterior lateral borders approximately 
equal to the posterior lateral borders. The middle three costals nearly 
equal in size, the fifth being much smaller and the shortest of the series. 
Nuchal long and narrow, usually with a very small median notch. Anter- 
ior border of the first marginal often but not necessarily finely denticulate. 
Posterior margin of the carapace either weakly serrated or unserrated, 
and with a very small median (caudal) notch. Plastron very large and 
wide, fully equalling the opening of the shell, exceeding in this respect 
the plastron of both marginata and belli; both anterior and posterior 
lobes truncate. Length of the posterior plastral lobe approximately one- 
half the width of the plastron, about equalling the total width of an 
abdominal scute at the point of the bridge. Gulars with a finely denticu- 
late anterior margin, and with the anterior lateral angles slightly pro- 
longed into a small knob. Pectoral scutes narrow. The interanal suture is 
usually the longest, but in some cases is equalled, and in a few exceeded, 
by the interabdominal suture. The interhumeral and interfemoral sutures 
are the shortest and are usually approximately equal, though either may 
be a bit shorter than the other. In only one specimen on hand the inter- 
humeral is shorter than the interfemoral suture. Inguinal large, axillary 
small. Head moderate in size. Snout short and bluntly pointed; nostrils 
anterior, terminal, and close together. Upper jaw with a small median 
notch and with a very small cusp on each side of it; the cutting edge is 
practically smooth, but sometimes with very faint denticulations. Alveo- 
lar surface narrow, with poorly developed median ridge. The limbs are 
strong; digits fully webbed to the base of the claws; claws 5-4, short in 
females, long in males. Tail slender, its proportions varying with the sex 
of the individual. 

CoLoRATION.—Carapace much less highly decorated than in either of 
the preceding species. Carapace dark brownish olive to nearly black. 
The mid-dorsal line is usually wide and very conspicuous; it starts at the 
tip of the nuchal and extends through or onto the caudals, sometimes 
bifurcating on the latter. It varies from yellow to blood red; often it is 


148 ILLINOIS BIOLOGICAL MONOGRAPHS 


vermillion. Anterior and anterior-lateral margins of the second, third, 
and sometimes the fourth vertebral scutes bordered with straw-color or 
yellow. Anterior margins of the second, third, and fourth costal scutes 
bordered with the same color. Individuals show a great variation in the 
width and conspicuousness of these color bands, but they are much more 
pronounced than in marginata or bellii. The marginals show little red 
dorsally, the area being confined usually to a single short, transverse line 
or a spot at the margin; the remaining marks consist of lines, comas, 
U- and S-shaped marks of straw yellow. Plastron uniformly yellow 
(Hurter (1911): “deep red in spring;” a condition the writer has never 
seen in spring specimens). Ventral surface of the marginals with bright 
red median area, bordered toward the sutures with black or dark olive, 
which dark areas contain irregular yellow mottlings. Axillary and 
inguinal scutes marked with red and yellow on the same dark ground 
color. Usually a dusky longitudinal area across the suture between the 
marginals and the lateral edge of the wing of the pectoral and abdominal 
scutes on the bridge. Soft parts dark olive, almost black, striped with 
yellow and red, those markings on the head and neck showing much 
variation but usually as follows: a yellow band from under the nostrils 
to the angle of the upper jaw; a yellow line from the dorsal margin of 
the nostril, running through the orbit and stopping shortly beyond it; two 
yellow bands, often quite broad, start above and below the angle of the 
jaw, shortly unite and extend as a broad band down the neck, grading 
into vermillion about half-way down the neck; a yellow line starts on 
the tympanum and extends down the neck; a broad yellow band starts 
at the posterior lateral dorsal portion of the occiput and extends down 
the dorsal lateral side of the neck, grading into vermillion and branching 
near the body to send a posterior branch toward the front leg. On the 
ventral surface, a yellow line starts at the symphysis of the lower jaw 
and quickly bifurcates, enclosing an olive area with yellow lines within 
it; these yellow lines grade into vermillion and fuse again into a single 
red line near the base of the neck. Between these more conspicuous 
lines are many faint and irregular lines of straw yellow. The top of the 
head is mottled and lined with the same color. Fore limbs with two 
conspicuous yellow-bordered red bands and irregular yellow lines. Hind 
limbs lined and dotted with yellow-margined red areas. Flesh of the 
axillary and inguinal regions of a similar color. Tail with two dorsal 
lateral yellow lines. 


YounG.—Nearly circular in shape. The carapace of newly hatched 
individuals tends to be a trifle less depressed than in the other turtles of 
the genus, and as the vertebrals have quite a slope, the median line is 
quite sharp, giving a hint of a very slight keel. The surface of the 
carapace is finely granular in these newly hatched individuals, but this 


THE TURTLES OF ILLINOIS—CAHN 149 


granulation disappears at an early date. The mid-vertebral stripe is wide, 
brilliant, and very conspicuous, but the yellow edges of the vertebral and 
costal scutes are entirely absent (28-mm specimen). The dorsal surface 
of the marginals shows a conspicuous lateral marginal spot of red, and 
the remaining dorsal surface of these scutes is finely reticulate. The 
ventral marginals show a red area near the anterior suture, with a black 
area toward the posterior margin, this dark area with a median yellow 
line. The major color lines described above are usually clearly indicated. 

SEX DIFFERENTIATION.—Males with claws on the second, third, and 
fourth digits of the fore limb; long, slender, and curved. Tail of the 
male is just short of being half the length of the plastron, and less 
than a third that of the plastral length in the female. In the male 
the anus opens well beyond the posterior: margin of the carapace. 


GrocGRAPHIC DIsTRIBUTION.— 
Chrysemys picta dorsalis is dis- 
tinctly of southern and southwest- 
ern distribution, the exact limits 
of whose range cannot at the 
present time be stated with accu- 
racy. Hurter (1911) gives its 
range as “from the Gulf of 
Mexico up the Mississippi River 
to the southeastern part of Mis- 
souri.” Siebenrock (1909) re- 
ports it from Mississippi and 
Louisiana, while Yarrow (1882) 
records it only from Mississippi. 
Hurter and Strecker (1909) re- 
cord it from northeastern Arkan- 
sas. Hurter (1911) reports it 
from the extreme southeastern 
corner of Missouri, to which 
Blanchard (1924) adds another 
record for the same region. In 
Louisiana, Beyer (1899) reports 
it as of general distribution in the 
state west of the Mississippi, but 
not common. It is not recognized 
at all by Davis and Rice (1883). 
The writer has taken it commonly at Reelfoot Lake, Tennessee. Ap- 
parently, then, the range is limited to the lower Mississippi Valley, and 
for the most part to the region west of the river. 


Map 15.—Chrysemys picta dorsalis. 


150 ILLINOIS BIOLOGICAL MONOGRAPHS 


ILLinoIs Recorps.—There is no published record of the occurrence of 
this turtle in Illinois. The writer first became acquainted with the species 
in the Reelfoot Lake country, where it is very common. Subsequent 
search in southern Illinois brought some thirty specimens from Cairo, 
Metropolis, Chester, and Horseshoe Lake in Alexander County. In all of 
these localities typical dorsalis was found, as well as a number of the 
hybrid forms previously discussed. It is not, however, common in the 
state. We must say, then, that dorsalis is confined to the extreme south- 
ern tip of Illinois, with a slight extension of its range up the Mississippi 
River to Chester. 


Hasitat.—Chrysemys picta dorsalis is distinctly more of a pond 
turtle than an inhabitant of rivers or streams, and shows more decided 
preferences in this direction than either of the preceding two members 
of the genus. In the southern tip of the state it is found in shallow weed- 
choked or rush-grown ponds, often temporary in nature, and often in 
water but a foot or less in depth. In consequence of the shallow nature 
of these ponds, the water therein has a higher temperature than is found 
in the deeper neighboring bodies of water at the same time of the year. 
It is often found in the over-flow ponds and backwaters of the Mississippi 
and Ohio rivers, as well as in the more permanent lakes. 


Hasirs.—So far as the writer has observed, dorsalis is very similar in 
its habits to marginata and bellii, except that it is perhaps a trifle more 
aquatic. It is most frequently seen with its head out of water, but cannot 
possibly be identified when thus placed unless one knows it to be the only 
Chrysemys in the region. During the warm days of spring and all 
through the hot summer, these turtles enjoy basking on exposed logs, 
lying relaxed as is common to the members of this genus. They are very 
timid, and scurry into the water when the least suspicious of danger. I 
have watched them thus sunning themselves in Horseshoe Lake and note 
that once disturbed, they are very slow about reappearing in their basking 
places. They are strong swimmers when necessity demands, but when 
undisturbed they may be seen walking slowly over the bottom in search 
of their food. They can remain under water for a long time, as observed 
in the laboratory, but in nature the duration of their submergence is 
very difficult to determine because of the numbers of the turtles generally 
present and the density of the aquatic vegetation which may effectively 
conceal their inconspicuous heads when poked to the surface. Except 
during the breeding season when they search for a nesting site, and in 
the event of the evaporation of their secluded pond when they are forced 
to migrate, the turtles rarely leave the water, though they are capable of 
easy and rapid locomotion on land. That they leave their aquatic en- 
vironment reluctantly is illustrated by the fact that when Horseshoe 
Lake dried up in 1930, hundreds of shells of these turtles were found 


THE TURTLES OF ILLINOIS—CAHN 151 


scattered over the lake bed, though the turtles would not have needed to 
migrate far to have found water. Might one guess that because the 
drying up of Horseshoe Lake was a new experience to the turtles living 
in it their migratory “mechanism” failed to function as it does in turtles 
living in ponds that regularly go dry? I noticed the same condition dur- 
ing the 1930 “low level” record of Reelfoot Lake in Tennessee: a pond, 
not connected by water to the lake, which under normal conditions 
would have measured some hundred yards in each direction, had dried 
up completely, and in the bed of this “dead” pond I found 116 dead 
dorsalis, with no other species of turtle represented. Yet in similar ponds 
half a mile away which had not dried up, I found dorsalis associated with 
many Pseudemys elegans, P. concinna, and P. troostii. There is no evi- 
dence either way on the subject of hibernation of this turtle in Illinois, 
but the writer doubts, because of the relative mildness of the climate in 
the region inhabited by the turtle, that the species goes into any pro- 
longed period of winter inactivity, if, indeed, it hibernates at all. 


Nestinc Hasits.—I have not been fortunate enough to have seen 
dorsalis digging its nest, and no description of the process exists in litera- 
ture. Yet at Horseshoe Lake I came close to it in June, 1930, when I 
caught a female just as she had finished her nest and was departing for 
the water. The nest was typical of that constructed by the other 
Chrysemys species, and contained six eggs. The nest was dug out, and 
it was noted that the soil was wetter than in the surrounding undisturbed 
area, indicating again the discharge of water from the cloaca during the 
process of nesting. 


Eccs.—The six eggs referred to above constitute the only set of 
eggs of the species the writer has been able to obtain. The eggs are 


TABLE 15.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Chrsyemys picta dorsalis 
(Measurements in millimeters; weight in grams) 


Carapace Plastron Tail 
Specimen Head Weight Sex 
Length } Width | Length} Width | Depth Total A-T 
132 105 125 89 46 19 41 36 307 2) 
132 104 125 88 46 20 40 32 300 2 
127 100 119 87 47 20 41 32 274 2 
128 98 123 83 42 20 42 34 249 2 
126 100 119 81 45 19 42 35 265 2 
125 102 120 89 51 20 40 30 304 g 
122 100 116 91 41 18 35 26 252 2 
114 91 107 76 42 18 43 31 200 2 
104 88 98 75 40 17, 39 30 172 2 
100 83 92 71 35 17 35 26 131 2 
99 75 80 60 29 14 40 25 91 (of 
87 70 80 60 33 15 30 Die 103 2 
81 66 iP By 28 13 42 29 74 lef 
81 66 71 55 26 14 37 22 60 (oy 
83 68 78 55 30 14 36 21 79 rot 
27 28 25 par 11 8 16 13 5 Im. 


152 ILLINOIS BIOLOGICAL MONOGRAPHS 


indistinguishable in size and texture from those of the other species of 
the genus, and it is very doubtful whether it would be possible to tell the 
eggs of marginata, bellii, and dorsalis apart by any means other than 
hatching. These eggs measure as follows (in millimeters): 31 x 19, 
31x19, 30x 20, 32x 19, 33x 18, 31 x 18, with an average of 31.3 x 18.8. 
No information as to the incubation period is available, but young turtles, 
evidently but recently hatched, have been sent to the writer from Cairo 
and Metropolis in both June and September. 


Foop Haxnirs.—The food habits of dorsalis are very similar to those 
of the preceding species of the genus, being distinctly omnivorous, with 
about an equal mixture of animal and vegetable matter usually found in 
the stomach. Of animal life, the following has been found: tadpoles, 
small crayfish, phyllopod crustaceans, gastropods, and an assortment of 
the larger aquatic insects and larvae, diving beetles (Dytiscus), Corydalis 
larvae, mayfly and dragonfly nymphs, Notonecta and caddis worms. Of 
vegetable matter, the chewed-up remains of grass, rootlets, and a variety 
of unidentifiable aquatic plants are almost always present. The scavenger 
habit is well developed and is indulged in when opportunity permits. 


GENUS PsEUDEMYS GRAY 


Pseudemys Gray 1855 Callichelys Gray 1863 
Ptychemys Agassiz 1857 Redamia Gray 1870 
Trachemys Agassiz 1857 Chrysemys (part) Boulenger 1889 


Nectemys Agassiz 1857 


Shell somewhat depressed, but not as much so as in the genus 
Chrysemys; posterior margin of the carapace serrated. Plastron trun- 
cate anteriorly, emarginate posteriorly. Abdominal and pectoral elements 
with well developed wings; axillary and inguinal elements approximately 
equal in size and relatively large. Alveolar surface of the jaws wide, and 
with a median ridge extending parallel to the margins. Digits fully 
webbed; 5-4 in number. Anterior digits long, with curved claws; fifth 
digit on the hind foot without a claw and in the form of a projection on 
the posterior margin of the foot. Fore limbs with rows of scales. Young 
with a distinct keel which may or may not persist in the adult stage. 


Pseudemys concinna (LeConte) 


Testudo concinna LeConte 1830 Clemmys concinna Strauch 1865 
Terrapene concinna Bonaparte 1830 Emys orthonyx Wied 1865 

Emys annulifera Gray 1831 Trachemys annulifera Gray 1873 
Emys concinna Duméril & Bibron 1835 Chrysemys concinna Boulenger 1889 
Emys labyrinthica LeSueur (Duméril 1851) Chrysemys labyrinthica Hay 1892 
Pseudemys concinna Gray 1855 Pseudemys labyrinthica Baur 1893 
Ptychemys concinna Agassiz 1857 Pseudemys vioscana Brimley 1928 


Malacoclemmys geographica (part) 
Agassiz 1857 


THE TURTLES OF ILLINOIS—CAHN 153 


DescripTIon.—Shell moderately depressed; carapace oval in outline, 
the point of maximum width varying with age, but in adults this region is 
usually in the immediate vicinity of the eighth marginal scute. Sides 


_ Pate 20.—Pseudemys concinna: A, Adult, ventral view. B, Adult, dorsal 
view. C, Adult, lateral view. D, Immature individual, lateral view; length, six 
inches. E, Same immature individual, ventral view. F, Newly hatched young, 
dorsal view. G, Head study of an adult. 


154 ILLINOIS BIOLOGICAL MONOGRAPHS 


with uniform slope, but with a distinct posterior flare involving the 
marginals from the seventh backward; anterior flare less marked. First 
vertebral scute urn-shaped, its lateral borders sinuous; second, third, and 
fourth vertebrals approximately as wide as long, and narrower than the 
costals; fifth vertebral wider than long, approaching trapezoidal. Costal 
scutes with more or less conspicuous lateral, longitudinal rugae. Anterior 
three costals very large, all three wider than long; fourth costal much 
smaller and with its length and width about equal. The first costal is 
triangular; the remaining elements of the series quadrangular. Nuchal 
elongate, nearly twice as long as wide, its anterior margin straight. 
Anterior margin of the carapace with a shallow, rounded emargination 
involving the first pair of marginals and the nuchal. Posterior marginals 
with their posterior angles produced to form a serrated edge, beginning 
usually at the ninth scute and ending with an acute median posterior 
notch between the caudals. Plastron large. Gular with a bluntly rounded 
anterior-lateral angle. Pectoral scutes much wider than long. Abdominals 
very large. Posterior margin of the plastron with a deep median notch, 
The interabdominal suture is the longest; the interhumeral the shortest. 
Axillary and inguinal elements large, the latter protruding forward so 
as to cut off the greater part of the wing of the abdominal from con- 
tact with the marginals. Bridge wide, the angle of slope toward the 
carapace varying with the size (age) of the individual, being most abrupt 
in young specimens. Head moderate in size, the snout short and blunt. 
Upper jaw without a median notch or hook, the cutting edge entirely 
smooth, not serrate; alveolar ridge strongly tuberculate and wide through- 
out. Lower jaw very flat and with a median tooth; cutting edge serrated. 
Limbs strong, the digits fully webbed; claws 5-4. Tail short and stocky. 

CoLoRATION. 


Carapace with the ground color varying from brown- 
ish to olive green, with a superimposed complicated design of yellowish 
lines. In a general way these lines tend to run longitudinally upon the 
vertebral scutes and transversely upon the costals. On the costals these 
lines tend to form into concentric areas of indefinite shape, bordering on 
circles. In some specimens the costals bear a transverse yellow bar as 
conspicuous as that found in Pseudemys elegans. Marginals with a trans- 
verse yellow bar near the middle. On each side of this is a thinner 
yellow crescent, opening toward the adjacent suture, within which cres- 
cent is a poorly defined yellow spot; the crescents of adjoining scutes 
thus tend to form a circle containing two yellow spots. The plastron is 
uniformly yellow or straw color, or with a few dusky spots or sym- 
metrical dusky areas on the gulars and humerals. The amount and place- 
ment of these darker areas exhibit great variation. Bridge, axillaries, 
and inguinals with dusky longitudinal areas. Ventral surface of the 
marginals yellow, with large crescent-shaped dusky areas containing one 


THE TURTLES OF ILLINOIS—CAHN 155 


or more yellow spots. Head and neck dark olive, striped with yellow or 
yellow-green. A straight line extends from the snout to a point just 
posterior to the orbit. Another line starts at the orbit, extends backward 
and widens on the neck. A third stripe starts at the posterior angle of 
the orbit and extends backward and downward, joining by a vertical 
branch, which passes the anterior margin of the ear, a fourth stripe which 
starts at the mid-ventral margin of the orbit. This fourth stripe is very 
wide and conspicuous. At the posterior angle of the mouth this stripe 
is joined by a conspicuous band from the mid-lateral margin of the 
lower jaw, thus forming a large “Y” around the posterior angle of the 
mouth. From the symphysis of the lower jaw a stripe starts backward, 
to bifurcate and extend as two irregular stripes down the neck. Often 
another stripe is to be found between these bifurcations. The upper jaw 
is lined with yellow. Tail, limbs, and feet with conspicuous yellow lines. 
The skin in the inguinal region is white, immaculate. 

Younc.—The young possess a distinct median keel, which disap- 
pears in individuals about half-grown, leaving no trace in the fully adult 
specimens. This keel is most marked on the posterior part of the second, 
on the third, and on the anterior part of the fourth vertebral scutes. 
The plastron shows considerable dusky color, arranged in symmetrical 
design which is usually more pronounced on the anterior elements, and 
faint traces of portions of this pattern may remain even in very large, 
mature individuals. There are usually two black spots on the bridge. 
The snout is very short and blunt; the eyes are prominent. Young speci- 
mens tend to have their maximum width near the middle of the carapace, 
this shifting posteriorly with age. 

Sex DIFFERENTIATION.—Males with claws of second, third, and 
fourth digits of the fore feet exceedingly long, at least three times the 
length of the other claws. The tail is longer in the male than in the 
female, and the anus lies beyond the rim of the carapace in male 
individuals. 

GEOGRAPHIC DistTRIBUTION.—Pseudemys concinna is a southern turtle 
which, for some reason or other, is hardly mentioned in lists or in litera- 
ture dealing with regional herpetology. Siebenrock (1909) records it as 
from the southern states, from Missouri and North Carolina to the Gulf 
of Mexico, excluding Florida; Boulenger (1889) gives a similar range, 
but does not exclude Florida. Loennberg (1894) reports it as the com- 
monest “‘cooter” in Florida! Stejneger and Barbour (1923) locate the 
range as ‘‘the eastern rivers from Georgia to southern Maryland.” For 
Louisiana, Beyer (1899) reports it as common in the southern portions 
but rarer inland except near large bodies of water; Strecker and Hurter 
(1909) say that specimens from Arkansas previously reported as P. 
concinna are in fact P. texana, a western close relative. Strecker (1915) 


156 ILLINOIS BIOLOGICAL MONOGRAPHS 


corrects Yarrow (1882) in the report of P. concinna from Texas, saying 
these are probably P. mobilensis Holbrook, and he further points out the 
hopeless confusion in Texas records of texana and mobilensis. Hay 
(1892) includes it in his Indiana list on the basis of the report of Gar- 
man (1892) from the Wabash River, though he has no further records 
to add. Rhoades (1895) records 
it from Tennessee, and the writer 
has taken exceedingly fine, large 
specimens in abundance from 
Reelfoot Lake in that state. It is 
not recorded from Alabama by 
Haltom (1931). The writer has a 
suspicion that the two new species 
of the genus Pseudemys described 
by Brimley (1929) under the 
names of P. vioscana (Louisiana) 
and P. elonae (North Carolina) 
are synonymous to P. concinna, or 
at best, subspecies of it. 


Ittinois Recorps.—The only 
published Illinois record for Pseu- 
demys concinna seems to be that 
of Garman (1890; 1892) of a 
specimen sent him by Dr. Shenck 
from Mt. Carmel, on the Wabash 
River, for it is not mentioned by 
Davis and Rice (1883). The 
writer has specimens from the fol- 
lowing localities: Mt. Carmel, 
Chester, Metropolis, Cairo, Eliza- 
bethtown, Murphysboro, Union 
County, and Horseshoe Lake in Map 16—Pseudemys concinna. 
Alexander County. 


Hasitat.—In the southern portions of its range, in which it is an 
abundant species, Pseudemys concinna apparently frequents brackish 
water, according to True (1884). In the northern limits of its range, 
however, the turtle is found only in the larger rivers and lakes, avoiding 
the smaller streams and temporary ponds. It is abundant among the 
cypresses of Reelfoot Lake, Tennessee, where the relatively warm, shal- 
low water and the abundance of aquatic vegetation seem to afford it a 
most congenial environment, for specimens reaching a length of 375 mm 
and a weight of over 4000 grams are not at all rare there. The shallow 
water of Horseshoe Lake in southern Illinois affords it a congenial 


THE TURTLES OF ILLINOIS—CAHN 157 


habitat, but here the specimens do not attain nearly so great a size. In 
this lake the species was exterminated when the lake went dry in the 
late summer of 1930; it will be interesting to note whether the species 
rehabilitates itself there. It has not done so to date (1933). When asso- 
ciated with the larger rivers, the turtles are most frequently met with in 
the backwaters and in the sluggish bays, seldom out in the main channel. 
Quiet, shallow, warm water, and an abundance of vegetation on a soft 
bottom seem to be their environmental requirements. 

Hasits.—In.1892 Hay wrote that “not much appears to be known 
about the habits of this terrapin,” and the same can truthfully be written 
after a lapse of forty years. It has been sadly neglected and should be 
thoroughly investigated in the south where it reaches its optimum; it 
is too rare in Illinois to do much with except over a long period of time. 
The observations herein recorded were made at Reelfoot Lake, and from 
notes and material submitted to the writer from this lake and from 
Horseshoe Lake in Alexander County, Illinois, by field workers. 

Pseudemys concinna is decidedly aquatic in its habits. It seldom 
leaves the water except to lay its eggs, spending most of its time in water 
from two to five feet deep. It spends a large part of the time sub- 
merged, either resting on the bottom or walking slowly about in quest of 
food, coming to the surface periodically for air. When at the surface, 
only the head protrudes, the shell remaining at an angle of about 45°, 
completely hidden. In this position the turtles remain for a long period, 
apparently motionless, but this surface drifting is only done when the 
water is smooth; if there are any waves at all they get their air imme- 
diately and submerge again. They are fond of basking, and crawl out on 
submerged logs or up on cypress knees, and remain for hours enjoying 
the warmth of the sun. I have seen logs lined with an assortment of 
P. concinna, P. elegans, P. troostii, and Chrysemys picta dorsalis, so 
thickly that sometimes they are piled up two deep. Pseudemys concinna, 
however, is very timid and wary; constantly on the lookout for danger, 
the least suspicious movement sends them off into the water, and once 
frightened, they are very careful for hours afterward. I have spent 
hours trying to capture specimens with a long handled dip net from a 
silently paddled boat, almost always without success. While they utilize 
every possible basking space available out in the water, I have never seen 
one basking on shore. 

On land they are rather slow and awkward, due to the bulk and 
weight of the shell, and among the tangle of cypress knees they have 
great difficulty in traveling on shore. When the fishermen take in their 
fish nets they frequently have many of these turtles in their catch. If 
they throw them ashore into the woods, as they frequently do, a great 
many of them never succeed in regaining the water, as witnessed by the 


158 ILLINOIS BIOLOGICAL MONOGRAPHS 


numerous skeletons I have found about the lake. The large turtles get 
penned up by the cypress knees and cannot climb over them or appar- 
ently find their way out of the maze. They show little intelligence in 
solving the problem and the result is often fatal. If taken from the water 
and placed on land, the turtles show no offense whatever, neither attempt- 
ing to escape nor to bite. The head and neck are drawn in as far as 
possible, and the legs pulled up under the shell, and thus they are likely 
to remain for hours. Once they get under way their progress is quite 
slow, while in the water their movements are powerful and rapid. They 
are excellent swimmers. 

Nestinc Hasirs.—The building of the nest has never been described 
so far as the writer knows, and he has no data to offer other than that 
they nest in sandy localities not far removed from the water. The season 
of nesting is reported as early June for the Reelfoot Lake country, and 
this would seem, from the condition of the eggs taken from females by 
dissection, to be about correct. While the writer has several sets of eggs 
dug from nests, no nest so far discovered has been more than about 100 
feet from water. 

Eccs.—A large female of Pseudemys concinna, sent to the writer 
from Reelfoot Lake in late May, 1931, had nine eggs in the oviduct, 
with the shell already deposited. The eggs were all ready to be laid, and 
are typical of the eggs of the species. They were elliptical and are 
covered with a hard, white shell of fairly coarse, granular structure. 
They measure as follows (in millimeters): 40x28, 42x26, 38 x 26, 
37 x 22, 36x 26, 35x 25, 35x 26, 40x 25, 36x 26; average: 37.6 x 26.1. 
There are no data on the period of incubation. The smallest specimen 
which the writer has is an individual with a carapace length of 39 mm, 
which was caught and sent in from Reelfoot Lake in late September, 
1931, and was undoubtedly a very recently hatched individual. 

Foop Hapits.—This species is largely carnivorous in its diet, feeding 
upon almost any animal matter that is available. From the stomachs of 
specimens examined in the field the following items have been noted: 
crayfish, tadpoles, small fish, gastropods, dragonfly nymphs, Corydalis 
larvae, water beetles, and an assortment of forms obviously picked from 
the surface, including grasshoppers, crickets, caterpillars, and various 
dipterous and hymenopterous insects. The scavenger habit is well de- 
veloped and I have observed the turtles feeding upon dead fish floating 
at the surface. They do not, however, practice this scavenger habit along 
the shore. Some vegetable.matter is usually present in the digestive sys- 
tem, this representing aquatic sedges, algae, and numerous shallow-water 
plant species. In Florida, Loennberg (1894) reports that they feed largely 
upon vegetable matter. 


THE TURTLES OF ILLINOIS—CAHN 159 


Economic ImportaNce.—Pseudemys concinna is far too rare in Ili- 
nois to be of any economic importance. To the southward, however, 
where it is abundant and where it reaches a large size, it is undoubtedly 
an item of human consumption, though it is not mentioned by Clark 
and Southall in this connection. Loennberg says that the meat is white 
and very palatable. 


TABLE 16.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Pseudemys concinna 
(Measurements in millimeters; weight in grams) 


Carapace Plastron Tail 
Specimen | Head | Weight Sex 
Length} Width | Length | Width | Depth | Total A-T 


330 216 293 171 107 61 45 38 3794 2 
326 232 300 181 113 55 45 41 3772 ie} 
219 156 194 119 66 87 40 26 966 c 
213 153 192 116 67 80 40 ZS 936 c 

75 63 (iP) 47 31 i) 10 13 64 Im. 


The Pseudemys elegans-troostii Problem 


When the writer first began collecting material for this monograph 
he was rather puzzled at first by the difficulties encountered in obtaining 
females, eggs, and young of Pseudemys troostii, a rather common species 
in the state. A search of the literature yielded nothing on the life history 
of the species, and, more confusing still, a search of the larger or more 
opportunely placed museums failed to unearth any of these specimens. 
An abundance of material was available from Illinois, and many dozens 
of specimens passed through the laboratory for study and examination. 
However, every good example of troostii proved to be a male. It was 
not long, furthermore, before a gradation between males of troostti and 
elegons was noted, and an entire and complete series of intergrada- 
tions between typical elegans on the one hand and typical troostu on the 
other was obtained. This series showed the increasing darkening of the 
carapace toward the troostii end, the gradual obliteration of the trans- 
verse yellow bar on each costal scute, the increasing amount of dark 
mottling on the plastron, and the gradual obliteration of the bright red 
postorbital band on the head through various deepening shades of brown 
and olive. While this series was being built up, correspondence with 
Mr. Percy Viosca at New Orleans brought out the fact that he had long 
believed that troostii was merely a melanistic male elegans. An oppor- 
tunity to examine a fine lot of both elegans and troostiu confirmed him 
in this view, and he published the results of his findings (1933). Know- 
ing, then, of Mr. Viosca’s findings, the writer skeletonized his series of 
elegans-troostii intergrades, and made a careful study of the skuils, 


160 ILLINOIS BIOLOGICAL MONOGRAPHS 


leg bones, and vertebrae. The results of this study only confirm the idea 
that elegans and troostii are inseparable; he can find no osteological 
character that will differentiate between them. Therefore, since there 
are, apparently, no troostii females, no troosti eggs or young, since a 
complete intergradation between elegans and troostii males has been 
demonstrated, and since there seems to be no anatomical or osteological 
character upon which they can be separated, he concurs with Mr. Viosca’s 
views. And since troostti is the older name (Emys troostti Holbrook 
1836; Emys elegans Wied 1839), Pseudemys elegans now becomes a 
synonym for Pseudemys troostii, which is most unfortunate in view of 
the fact that ex-troostii is only the melanistic male of the much more 
familiar ex-elegans! Such are, however, the laws of priority. In order 
to simplify matters and so as not to add unnecessarily to the confusion of 
names, these melanistic males will be discussed separately at the end of 
this section. 


Pseudemys troostii (Holbrook) 


(Red-head ; painted turtle; pond terrapin) 


(Synonomy for what has heretofore been called P. elegans) 


Emys troostii Holbrook 1836 Trachemys holbrookiit Gray 1873 
Emys elegans Wied 1839 Trachemys lineata Gray 1873 

Emys cumberlandensis Holbrook 1842 Pseudemys elegans Cope 1875 
Emys holbrookit Gray 1855 Chrysemys scripta elegans Boulenger 
Emys sanguinolenta Gray 1855 1889 

Trachemys elegans Agassiz 1857 Chrysemys elegans Hay 1892 
Clemmys elegans Strauch 1865 Pseudemys troostii Viosca 1933 


DescripTion.—Shell broad, depressed ; uniformly convex both toward 
the sides and along the anterior-posterior axis, this median axis with but 
the faintest trace of a keel in the adult if, indeed, any trace is present; 
if present, this trace is more conspicuous toward the posterior end of the 
carapace. Carapace emarginate posteriorly, with a notch between the 
scutes and a second notch within the boundary on the scute at a point 
about one-third the distance from the posterior margin. These serrations 
begin faintly on the eighth (occasionally on the seventh) marginal. The 
vertebral scutes are all of very nearly equal length. The first vertebral 
approaches a square, being approximately as long as wide, and is slightly 
urn-shaped. The second, third, fourth, and fifth vertebrals are wider than 
long, the second and third being the largest of the series, though the fifth 
is usually almost as wide but is distinctly shorter. The anterior margin 
of the third and fourth vertebrals is longer than the posterior margin, 
while the anterior margin of the second and fifth is shorter than the pos- 
terior. The costals are large and are arranged in a series decreasing in 
size posteriorly; the second and third are rectangular, the fourth 


THE TURTLES OF ILLINOIS—CAHN 161 


approaches the square. The nuchal is triangular, narrow, and usually has 
a weak median notch. There is a notch near the middle of the border 
of the first marginal. The marginals flare posterior-laterally beginning 
with the eighth scute, though the caudal marginals do not flare, carrying 
out as they do the posterior curvature of the carapace. There is a deep 
caudal notch. The surface of the carapace is more or less wrinkled, with 


PLATE 21.—Pseudemys troostii: A, Adult male, ventral view. B, Adult female, 
dorsal view. C, Newly hatched young, ventral view. D, Newly hatched young, 
dorsal view. E, Adult, lateral view. (This is the form previously known as 
Pseudemys elegans.) 


162 ILLINOIS BIOLOGICAL MONOGRAPHS 


interrupted longitudinal rugae on the costal scutes especially. The con- 
spicuousness of these rugae varies greatly in different specimens. The 
plastron is very slightly rounded anteriorly, and shows a broad, shallow 
emargination posteriorly. The posterior lobe of the plastron is narrower 
than the anterior lobe, and approximately two-thirds the width of the 
carapace. Gular scutes triangular, the anterior-lateral angle slightly and 
bluntly protruded. Abdominal scutes longer than wide if the bridge is 
excluded, and are the longest of the plastral elements, with the longest 
suture. Interfemoral suture about equalling the interhumeral suture. 
Anal scutes trapezial, with a long interanal suture. The bridge is wide 
and rises rapidly and evenly to the marginals. Axillary and inguinal 
scutes present and well developed, the inguinal the larger of the two. 
The head is of moderate size, with the snout very short and blunt. The 
edge of the upper jaw is convex along the posterior margin and there 
is a shallow but distinct median notch. The tip of the lower jaw curves 
upward to fit into this notch. Alveolar surface of the upper jaw with a 
low, very finely serrated ridge. Limbs well developed and the feet fully 
webbed. There are five claws anteriorly and 4 posteriorly. Tail moder- 
ate, projecting beyond the carapace. 


CoLoRATION.—The carapace is olive brown, with a complicated pat- 
tern of yellow lines and black stripes. On the first two vertebral scutes 
the lines tend to run longitudinally, becoming irregular and wavy on the 
posterior scutes. A yellow band of varying width and intensity extends 
transversely down the middle of the costal scutes, with other bands of 
black and yellow roughly paralleling it. There are two conspicuous wide 
black bands on each of these scutes. The marginals, both above and 
below, show a black spot on the intermarginal sutures, this surrounded by 
vague concentric circles of yellow and black. The black spot is large 
and very conspicuous on the ventral side. The plastron is yellow with, 
typically, a conspicuous black blotch on each scute, and more or less of 
a black mottling down the mid-ventral suture. Occasionally the plastron 
is almost entirely black. The bridge often has black spots confluent into 
a longitudinal band; sometimes this mark is absent. The axillary and 
inguinal plates are marked with black. The head shows many stripes of 
yellow or orange, fine dorsally and coarser ventrally and laterally. A 
very conspicuous blood red or orange red stripe starts at the posterior 
margin of the eye and extends backward upon the neck, becoming narrow 
posteriorly, and affords an excellent field mark for the identification of 
the species. A broad yellow stripe starts under the eye and extends 
backward along the neck, passing between the tympanum and the jaw, to 
be met by a stripe from the middle of the jaw at the angle of the mouth. 
On the under side of the head, a mid-ventral yellow line starts at the 
mandibular tooth, sending two diverging lines along the neck; a second 


THE TURTLES OF ILLINOIS—CAHN 163 


broad stripe starts about mid-way between the symphysis and the angle 
of the jaw and extends toward the stripe starting below the eye, and may 
or may not reach it. The stripe which in Pseudemys concinna starts 
above the eye and extends to the neck, is missing. The legs are striped 
with yellow, as is the tail; the fore limbs show two very conspicuous 
parallel yellow bands on the anterior margin. 

Younc.—The young show the typical markings and coloration of the 
non-melanistic adult, but the vertebral keel is high and conspicuous, be- 
coming more and more obscure with advancing age and increasing size 
of the individual. The concentric nature of the blotches is more pro- 
nounced, especially in the marginal and plastral elements. Description 
of a 30-mm individual: carapace: bright green, all scutes marked with 
fine parallel black lines arranged either in bands or in concentric figures ; 
also true of. the marginals. The yellow stripes of the adult show clearly 
on the costals; marginals edged with yellow from which edge a yellow 
mark extends toward the costals, forming a “T.’”’ Plastron yellow, each 
scute with a black spot formed by alternating concentric areas of black 
and yellow, usually with a light center. Ventral side of the marginals 
with a similar spot formed by a series of concentric black rings over- 
lapping the intermarginal sutures. Similar spots are on the wings of the 
abdominals and on both the inguinal and axillary plates in typically 
marked specimens. Head and soft parts elaborately marked with bands 
of yellow, green, and black. Of these the most conspicuous is a Y-shaped 
band starting ventro-laterally on the neck and forking behind and below 
the mouth, one arm terminating at the margin of the lower jaw. A 
second Y-shaped band starts at the symphysis of the lower jaw, forking 
almost at once to send the arms of the “Y’’ down the ventral side of the 
neck. The crimson area behind the orbit is fully developed and con- 
spicuous, blending into a pale green stripe which runs back along the 
side of the neck. Limbs and tail green, streaked with bright yellow. 


Sex DIFFERENTIATION.—The tail is much longer in the female than 
in the male. In the female the anal opening lies beyond the posterior edge 
of the carapace, while in the male this opening lies below the carapace. 
The red band of the male is likely to be brighter than that of the female, 
especially in the early spring and during the breeding season. The claws 
of the front feet of males are very long, slender, curved; those of the 
female are short and stout, and hence more practical for digging the nest. 

GroGraPHic DistripuTIoN.—Pseudemys troostii is distributed over 
the lower two-thirds of the Mississippi Valley, from northern Illinois, 
Indiana, and Ohio southward to the Gulf of Mexico. It is not listed as 
occurring in Ohio by Smith (1882), or by Morse (1904), though that 
state is included within the range of the species by Stejneger and Barbour 
(1923). It is not recorded from Michigan by Ruthven et al (1928). 


164 ILLINOIS BIOLOGICAL MONOGRAPHS 


PLATE 22.—Pseudemys troostu: (Above)—Sex differentiation as illustrated by 
the claws of the fore feet—left, female; right, male. (Below)—Variations in 
plastral markings of melanistic males; /eft, markings nearly typical of the non- 
melanistic individuals; right, practically the extreme exhibited in melanistic 
individuals. 


THE TURTLES OF ILLINOIS—CAHN 165 


Hay (1892) reports it from Indiana, but very sparingly; it is recorded 
from Vigo County, Indiana, by Blatchley, and Evermann and Clark 
(1920) report it as the rarest turtle in Lake Maxinkuckee. It has not 
been recorded from Wisconsin, though it occurs in Illinois very close to 
the Wisconsin line, so that the writer might venture a guess that it might 
be found in Lake Koshkonong. Blanchard (1922) records it from 
western Tennessee, and the writer has found it very abundant in Reel- 
foot Lake in that region. It is one of the commonest turtles of Louisiana 
(Beyer, 1899), but apparently does not extend far eastward. Haltom 
(1931) reports it for but one region in Alabama. Strecker (1915) re- 
ports it from the entire length and width of Texas; Hurter and Strecker 
(1909) have one record from northeastern Arkansas, and Hurter (1911) 
has numerous records from Missouri. Yarrow (1882) records it from 
Mexico, Kansas, Tennessee, Louisiana, Missouri, and from the Yellow- 
stone River; his report of the species from South Carolina is based on a 
specimen of Pseudemys scabra. 


Ittrno1s Recorps.—For Illinois, the species is reported as from 
the southern part of the 
state by Davis and Rice (1883). 
For the Quincy region, Garman 
(1888) records it as frequent in 
sloughs ; in his later report (1892) 
he records it from the larger 
streams in the southern two- 
thirds of the state, and gives 
Quincy, Henry, Peoria, Pekin, 
Havana, and Mt. Carmel as spe- 
cific localities. Hurter (1911) re- 
ports it from St. Clair and Madi- 
son counties, and Hay (1893) 
from Mt. Carmel. The Field 
Museum has specimens from 
Liverpool, Maeys, Olive Branch, 
and Mt. Carmel. The writer has 
examined specimens from the fol- 
lowing localities: Havana, 
Chester, Meredosia, Danville, 
Sterling, Carlysle, Louisville, 
Cairo, Horseshoe Lake in Alex- 
ander County, Camden, Mt. Car- 
mel, Peoria, Quincy, Shawnee- 
town, Metropolis, New Haven, 
Carmi, Clay City, Lawrenceville, Map 17.—Pseudemys troostii. 


166 ILLINOIS BIOLOGICAL MONOGRAPHS 


Centralia, Murphysboro, DeSoto, New Athens, Vandalia, Carlinville, 
Hardin, Bureau, Harrisburg, and Petersburg. The turtle is common in the 
Illinois River, increasingly so toward the south, and is much more 
adundant in the southern part of the state than in the northern portion. 


Hasirat.—Pseudemys troostu is found most commonly in large, quiet 
waters, and only rarely in fast water. Thus it is an abundant species 
in the wide reaches of the larger rivers of the state—the Mississippi and 
Illinois—as well as in the over-flow lakes along the Mississippi and 
Illinois bottoms. Toward the headwaters of the various rivers in which 
it occurs, the species becomes increasingly rare, and never does it reach 
beyond the region where the rivers are wide and slow-flowing. Soft bot- 
tom, such as silt or mud, seems to be the most congenial, and a consider- 
able growth of aquatic vegetation is highly desired by the turtles. In the 
spring, when the larger streams grow into flood conditions, if the turtles 
are out of hibernation they escape the turbulent conditions of mid-stream, 
and enter the flooded bays and ponds, where they remain until the re- 
cession of the water drives them back to the river. Those ponds which 
are permanent will likely have a permanent troostii population. Again, 
it is more of a pond than a river species; hence the local name of “pond 
terrapin.” 

Hasits.—Distinctly aquatic in its habits, Pseudemys troostii is seldom 
found on land except during the nesting season or when traveling from 
pond to pond or from pond to river. It is a quick, active species, which 
indeed is very much at home in the water, though its movements are not 
as rapid as those of the soft-shelled turtles or, for that matter, as the 
turtles of the genus Chrysemys. This is probably due to the bulk and 
weight of the shell. If great beds of aquatic vegetation are available, the 
turtles wander around, in and out, among the thickest of the growth, 
their perambulations often wearing open pathways or tunnels through 
it. As a result of their selection of quiet, vegetated regions they are, 
like turtles of the genus Chrysemys, frequently found with dense growths 
of algae on the carapace, and little growths of the colonial protozoan 
E pistylis articulata are often found upon the plastron. If logs are avail- 
able out in mid-stream, the turtles pile up on them two and three deep, 
and spend the hotter hours of the mid-summer days sunning themselves 
in the security of their island retreat. If logs are not available, their 
heads may be seen poked out above the surface, just beneath which the 
turtles lie at rest for long periods at a time, apparently quite as relaxed 
as if they were upon a more secure footing. Always watchful, the least 
sign of anything dangerous sends them below the surface like a flash, 
and once frightened, they are more cautious than ever. Refuge is sought 
at once in the heart of the densest of the vegetation, to the very bottom 
of which they burrow immediately, remaining motionless until the fright 


THE TURTLES OF ILLINOIS—CAHN 167 


reaction wears off. The sloping bank of the water’s edge is seldom 
utilized and one rarely sees a turtle of this species basking in such a 
location. If cornered on land, the turtle withdraws completely within its 
shell, the withdrawal of the head being accompanied by a hissing sound 
as the air is expelled from the lungs to accommodate the incoming bulk 
of the head and neck. If bothered too much, it shows a reluctant incli- 
nation to snap, a sort of half-hearted attempt that is but a poor offense 
at best. In captivity it refuses to eat for a week or two after its capture 
and is very timid, but once it becomes used to its surroundings, it grows 
very tame and will eat from the hand offering food, and follow it all 
over the aquarium. Agassiz (1857) reports that he has heard turtles of 
this species “emit a piping note.”’ The writer was astonished one night 
to hear a distinctly whistled note arise from one of his turtle pens, re- 
peated over and over again at irregular intervals. Quiet watching finally 
located the sound as coming from a half-grown turtle of this species, 
which periodically raised its head to the fullest extent of the neck and 
then ‘“‘whistled,” the note coming as the air was expelled from the lungs. 
For three days the turtle “whistled,” and then suddenly died. Dissection 
showed a small foreign obstruction lodged in the trachea, and the writer 
was able to reproduce the whistled note by blowing through the trachea 
with a blow pipe. 


NestinGc Hasits.—Pseudemys troostii nests in clear sandy areas not 
far removed from the water. The egg laying usually begins during the 
third or fourth week of June and is completed by the end of the first week 
of July. While there is considerable variation in the time of day at which 
nest digging and oviposition occurs, by far the greater number lay early 
in the morning, while a few lay late in the afternoon; it is rare to find 
this turtle laying during the day between eight in the morning and four 
in the afternoon. The female leaves the water slowly and cautiously; 
one glance at her will show that she has something quite definite on 
her mind even though she wanders up the bank in a leisurely, casual 
manner, her head well out, looking from side to side with considerable 
care. Now and again she pauses to scratch prospectively, but not being 
satisfied with the soil conditions, she goes on until she finds exactly the 
right spot. Here she begins to dig, using the hind feet in the process, the 
front feet remaining more or less fixed in their position. She digs 
steadily, throwing the loosened sand out behind her, pausing now and 
again to stare fixedly at some suspicious object she had not noticed 
before. The digging is not hurried, but gives one the impression of de- 
termination rather than haste. The hole is dug to a depth of between 
four and six inches, depending upon the ground conditions and the size 
of the turtle, and requires approximately thirty minutes for completion. 
The eggs are deposited one at a time as soon as the nest is finished, and 


168 ILLINOIS BIOLOGICAL MONOGRAPHS 


are laid at the rate of one about every 40 seconds until the complement 
is complete. If the female is disturbed while laying she usually shows no 
offensive reaction, but retires passively into her shell and waits. It takes 
considerable disturbance and actual physical violence to cause her to for- 
sake the hole while the laying is in progress, but the actual oviposition 
is suspended without great cause. When the last egg has been deposited, 
the dirt is raked into the hole and the eggs covered even with the 
surface, the hind legs dragging in the sand scattered during the digging 
process. With the location of the nest thus concealed, the turtle returns 
directly to the water, usually at a greater speed than she showed on leav- 
ing it. From an examination of the ovaries it has been ascertained that 
females become sexually mature and lay for the first time when they 
attain a carapace length of 7 to 714 inches. 


Eccs.—The eggs of this turtle are oval, with well and equally rounded 
ends, white, and of a rather coarse and granular shell texture. The 
number varies considerably, depending upon the size and age of the 
turtle. A large complement contains 20 eggs, and I once found a set 
containing 23, The average number of eggs is between 15 and 18, and 
small clutches of 6 or 8 eggs usually represent the first efforts of a 
young female. In size they average 37 x 22 mm, varying from 34x 21 
mm to 38.5x 23.5 mm; these figures are from seven different sets of 
eggs taken at Meredosia, numbering 121 eggs. Great numbers of nests 
of this turtle are found dug out, the old eggshells giving mute evidence 
of the activity of raccoons and skunks, which animals delight in turtle 
eggs. In the vicinity of Meredosia, on the Illinois River, the young 
hatch toward the end of August or early in September. Immediately 
after hatching they go directly to the nearest water and remain in the 
vegetation-choked shallows. 


Foop.—Pseudemys troostii is largely a carnivorous species, but is able 
to subsist for long periods on a strictly vegetable diet, as the writer has 
shown in the laboratory. In nature the food consists of tadpoles, crayfish, 
mollusks (mostly gastropods), the larger larvae and nymphs of aquatic 
insects, and small fish, of which the following species have been identi- 
fied: Notropis hudsonius selene, Umbra limi, Apomotis cyanellus, Helio- 
perca macrochira, and Perca flavescens. Usually a quantity of well-masti- 
cated vegetable matter is to be found in the digestive system, this consist- 
ing of the various aquatic plants of the region apparently without much 
discrimination as to species. In the laboratory it will eat chopped meat 
with avidity, and will also subsist on lettuce, apples, and to some extent 
on bananas. It has a strong scavenger tendency, and will be found feeding 
upon dead fish, amphibia, and even small mammals which find a watery 
grave. It will not, however, leave the water to feed upon dead matter 
upon the shore. 


THE TURTLES OF ILLINOIS—CAHN 169 


Economic Importance.—The three most important “‘food”’ turtles 
outside of the snapper (Chelydra) and the soft-shells (Amyda) are: 
Pseudemys troostii, Graptemys geographica, and Graptemys pseudogeo- 
graphica pseudogeographica. Oi these, troostii is the most common, but 
since it does not attain a size equal to that of the snapping turtle or the 
soft-shelled species, it is not used extensively for table purposes. How- 
ever, Clark and Southall (1920) report that troostii (i.e. elegans of these 
writers) appears commonly in the fish markets of Chicago, and they are 
sometimes shipped as far as Philadelphia and Washington from the 
Illinois River. The price of these turtles now ranges around 20 cents 
each. The meat is of high quality and delicious flavor. 


TABLE 17.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Pseudemys troostit 
(Measurements in millimeters; weight in grams) 


Carapace Plastron | Tail 
Succimcn | Head | = Weight Sex 
Length | Width | Length| Width | Depth Total A-T 
| 
| 
Maver vei cNatct afc acs 243 181 206 147 95 36 68 40 | 2035 2 
Deters heres tere 233 178 216 147 o4 35 54 35 | 2050 ) 
Sa SEES RABE 230 175 224 139 88 | 37 53 33 | 2006 2 
ee ieee ene 215 159 199 130 87 | 31 40 | 33 1320 2 
Saye erate ae cre 200 154 185 120 73 28 73 | 38 1005 2 
Oras nisi scores eet 196 145 188 109 76 31 50 40 1083 ol 
UL Ac POOR BEAD 195 152 186 120 72 28 | 50 39 1094 rol 
SB avstste, 2 siajeigie lee 192 151 184 126 73 28 | 50 36 1021 2 
Oreos 8 eee 189 | 154 178 78 65 27, 50 996 ic} 
OM yearecsecnicve =e 185 131 168 95 60 26 60 40 740 2 
RL See yctehs ace Pets are 170 132 157 100 58 25 70 34 637 (ot 
Tas ee ee 166 129 161 117 | 58 24 55 34 644 g 
Dee ceteris cyapsis. ve 156 122 151 100 55 25 46 | 545 | os 
1D a OUST eee 112 92 103 74 44 20 43 30 223. | os 
MS ns Se Sate teach 110 85 102 66 40 | 19 30 185 Q 
M Olen tee, 86 75 81 AY | 32 | 16 27 | 101 fou 
| t 


ParasiTEs.—This turtle, being an abundant species, is a good form 
for a study of turtle parasites, and affords a good collecting subject for 
class study in parasitology as it usually is rather heavily infested with 
a variety of forms. The writer has taken the following from this species: 
Neoechinorhynchos emydis (Acanthocephala), Allassostoma magnum 
and Polystomoides microcotyle (Trematoda), and Ophiotaenia testudo 
(Cestoda), this being the second record of this Magath species. 


Melanistic Males of Pseudemys troostu 
( Black-headed turtle ) 


(Synonomy of what has heretofore been called Pseudemys troostii) 


Emys troostii Holbrook 1836 Pseudemys troostii Cope 1875 
Trachemys troostii Agassiz 1857 Chrysemys troostu Boulenger 1889 


170 ILLINOIS BIOLOGICAL MONOGRAPHS 


Description.—These melanistic males, representing what, in the 
literature of herpetology to date, has been the original Pseudemys 
troostii, show the physical and structural characteristics of scute con- 
formation as already described for the non-melanistic forms, and hence 


PLaTteE 23—Pseudemys troostii, melanistic males: A, typical adult with a 
smooth carapace. B, Adult; shell with many fine rugae. C, Head study of a typical 
adult non-melanistic male. D, Head study of a typical adult melanistic male. 


THE TURTLES OF ILLINOIS—CAHN 171 


need not be repeated. There is but one feature which, while not at all 
constant, appears much more frequently in these turtles than in the 
typically colored forms; this is a rugous condition of the dorsal scutes, 
especially of the costals. These small ridges tend to follow the general 
outline of the carapace, and in extreme development may be a highly 
conspicuous characteristic of the specimen; again, they may be absent. 

CoLoraTion.—Carapace: dark olive to dark grayish brown, without 
any trace of light color markings. The sutures between most (if not all) 
of the scutes of the carapace are covered with black or very dark choco- 
late brown in an irregular pattern. The olive green ground color is 
often brightest on the three anterior marginals; on the ventral surface 
of the marginals, yellow replaces the olive green. In a fully melanistic 
specimen the entire carapace has the appearance of being dull and in- 
definite as to color markings. The plastron is pale yellow or straw, with 
a varying amount of black markings. On the anterior two-thirds of the 
plastron these black markings appear as streaks which follow the sutures 
for the most part, with the dark central area expanding posteriorly so as 
to cover most of the surface of the femorals and anals. In many cases 
one can observe traces of the last vestiges of the dark blotches so charac- 
teristic of the plastron of non-melanistic individuals. Occasionally there 
are black lateral patches on the abdominals. The bridge shows black 
patches along the sutures. The under side of the marginals shows a 
black patch or spot, the center of each spot falling upon a suture; hence 
a yellow bar reaching to the margin of each marginal scute, this repre- 
senting the ground color. Head, neck, and limbs of the same dead tone 
as the carapace, the head olive green, finely and inconspicuously striped 
with black. An inconspicuous dark olive-brown band extends backward 
from the posterior margin of the eye, replacing the brilliant red band 
of the typical non-melanistic individuals. Behind the eye it widens, to 
reach its maximum width dorsal and posterior to the ear, beyond which 
it again becomes narrow. The jaws are dark, spotted and lined with 
black. A short median stripe of yellow begins at the symphysis of the 
lower jaw and branches at once to send two conspicuous stripes down 
the under surface of the neck. The angle of the jaw lies between two 
brown bands, one arising from the posterior median margin of the orbit, 
the other arising from near the posterior lateral margin of the lower jaw. 
These bands unite posterior and ventral to the ear and extend as a single 
inconspicuous line down the neck. Both limbs and tail show only very 
faint color markings; the tail tends to exhibit a yellowish lateral stripe 
and a median dorsal brown stripe. All variations between the brightly 
colored typical individuals and the very dark, fully melanistic individuals 
may be found, but only in the males of the species. 

While dealing with the question of coloration, it is interesting to note 


OIS BIOLOGICAL MONOGRAPHS 


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THE TURTLES OF ILLINOIS—CAHN 173 


what Hay (1892) has to say: “This is a very beautiful and a charac- 
teristically marked species. It may readily be distinguished from C. 
elegans by the brown borders of all the scutes, and the absence of yellow 
stripes on the carapace. Both have a blood-red stripe along the neck.” 
It is obvious from this last sentence that Hay either did not have fully 
melanistic “troostii’’ or that he has made a composite description from 
several specimens; for the melanistic form, when fully developed so as 
to have lost all trace of the trans- 
verse yellow costal bars, does not 
have the blood-red stripe behind 
the eye, which stripe is character- 
istic only of “elegans.” 


DistTRIBUTION.—In_ order to 
bring out more conveniently the 
geographic distribution of the me- 
lanistic males as compared to the 
non-melanistic individuals, as re- 
vealed in the published literature, 
the writer wishes to revert for the 
purpose of this discussion only, to 
the old nomenclature used in this 
literature in which the melanistic 
form is treated as a distinct 
species, by calling the non-melan- 
istic forms ‘‘elegans” and_ the 
melanistic males ‘“‘troostii.” <A 
comparison of the distribution of 
these two forms is most easily 
made according to states as shown 
in Table 18. As to the distribution 
within Illinois, a glance at the two 
maps, showing the distribution of 
Pseudemys troostii (Map 17) and 


i a: Map 18.—Pseudemys troostu— 
of the melanistic males (Map 18), melanistic males. 


will show that these melanistic in- 
dividuals are more common in the southern part of the state than in 
the northern. 


From the foregoing information, certain generalized statements may 
be drawn, though until a more systematic and careful series of collec- 
tions is made throughout the Mississippi Valley we cannot delimit with 
any exactness the range of these melanistic troosti. It is fairly obvious, 
however, that where “elegans” is common, there, too, we find “‘troostii” ; 
(how Blanchard missed it around Reelfoot Lake, Tennessee, is a puzzle, 


174 ILLINOIS BIOLOGICAL MONOGRAPHS 


for here it is a very common species) ; that at no place is it as common 
as “elegans,”’ which is perhaps not surprising, as only one sex is involved; 
that it is not found outside of the range of “elegans”’; and that it is much 
more common in the southern part of the Mississippi Valley than else- 
where. Since it is not found throughout the range of “elegans,” and 
since it is found most abundantly in the southern part of the range of 
that form, are we to infer that there is a temperature factor involved in 
the production of these melanistic individuals? Although we cannot say 
for certain that all adult male “elegans” do not become melanistic in old 
age, this would seem to be the case. A series of measurements made on 
both “elegans” males and “‘troostii” follows. Carapace length in mm: 
“troostii”’: 217, 212, 210, 202, 200, 196, 193, 191, 177, 172. 
“elegans”: 196, 195, 192, 189, 185, 180, 166, 156, 112, 110, 86. 

The writer has found no example of melanistic “troostii’ smaller than 
172 mm, which might be considered as typical of the form, though inter- 
mediate, intergrading forms with “elegans” characters still visible have 
frequently been found below this size. Nor has he found any male 
“elegans” that equals in size the largest of the “troosti.” This might lead 
one to infer that “troostii’ is the very old male “elegans,” but such a 
statement is not permissible until a further study has been made, for the 
largest “elegans,” measuring well up into the “‘troostii’” series, show no 
signs of any melanistic tendency. 

So far as habitat selection is concerned, the melanistic “troostii”’ 
are always associated with the non-melanistic individuals: both are caught 
in the same net at the same time, though, as we have said, in fewer num- 
bers. In only one point of behavior could one note anything like a charac- 
teristic not pronounced in both. The non-melanistic “elegans” is a rather 
quiet, inoffensive, peaceful species, not given especially to snapping or 
pugnacious qualities in either sex; the melanistic “troostii,” on the other 
hand, frequently exhibits decided pugnacity. 


TABLE 19.—MEASUREMENTS OF ILLINOIS SPECIMENS OF MELANISTIC MALES OF 
Pseudemys troostit 


(Measurements in millimeters; weight in grams) 


: Carapace Plastron Tail 
aca Head | Weight 
Length} Width | Length! Width | Depth Total A-T 
Lae ee 217 155 193 113 70 29 65 45 1214 
oi. ae 212 151 188 117 72 28 75 39 1190 
Bete. |e 202 eal ayen tel 35 114 63 28 75 42 1039 
Ah eee 200 | 146 186 112 69 My 66 41 1002 
Se eee 191 | 148 171 81 66 28 70 40 965 
Odean 177 | 143 161 80 62 v7. 70 41 872 
Fie | 172 | 126 | 152 91 55 26 72 39 720 


THE TURTLES OF ILLINOIS—CAHN 175 


FAMILY TRIONYCHIDAE 


Trionychida Strauch 1862 
Chitradae Gray 1870 
Emydinadae Gray 1870 


Trionycidae Gray 1825 
Trionychidae Bell 1828 
Steganopodes (part) Wagler 1830 
Potamites Duméril & Bibron 1835 

ExtTerNaL Freatures.—Body extremely flattened, nearly circular in 
outline, both carapace and plastron without any epidermal skeleton com- 
posed of scutes, the dermal skeleton covered with a continuous leathery 
skin which is somewhat cartilaginous along the margin. Snout projected 
into a flexible fleshy proboscis, with terminal nostrils. Jaws partially con- 
cealed beneath fleshy lips; the ear is hidden. Head and neck completely 
retractile within the shell along a sigmoid curve. Digits 5-5, claws 3-3, 
only the three inner digits with claws, the unclawed digits concealed 
within the web. 

OstEOLocIcAL Fratures.—Dermal skeleton not completely ossified. 
Epiplastra separated from the hyoplastra by a T-shaped entoplastron ; 
marginal bones absent or at best forming only an incomplete series, not 
connected by ribs. Cervical vertebrae without transverse processes; the 
articulation between the last cervical and first dorsal vertebrae by the 
zygopophyses only. Mandible with articulary concavities. The outer 
border of the tympanic cavity is notched. Pterygoids not narrowed pos- 
teriorly and separated from each other. Basisphenoid joining the pala- 
tines. Pelvis is not anchylosed to the carapace or to the plastron., 


Genus AMYDA OKEN 


Amyda Oken 1816 Callinia Gray 1869 


Aspidonectes Wagler 1830 


Gymnopus Duméril & Bibron 1835 


Platypeltis Fitzinger 1835 
Pelodiscus Fitzinger 1835 
Potamochelys Fitzinger 1843 
Chitra Gray 1844 

Tyrse Gray 1844 
Trionyx Gray 1844 
Dogania Gray 1855 
Rafetus Gray 1864 
Aspilus Gray 1864 
Pelochelys Gray 1864 
Landemania Gray 1869 
Sarbieria Gray 1869 
Fordia Gray 1869 


Isola Gray 1873 

Oscaria Gray 1873 
Nilssonia Gray 1873 

Ida Gray 1873 

Yuen Heude 1880 
Psilognathus Heude 1880 
Temnognathus Heude 1880 
Gomphopelta Heude 1880 
Coelognathus Heude 1880 
Tortisternum Heude 1880 
Ceramopelta Heude 1880 
Coptopelta Heude 1880 
Cinctisternum Heude 1880 
Aspidertes Hay 1903 


EXxTerNAL Freatures.—Body extremely depressed, nearly circular 
in outline. Carapace and plastron without epidermal scutes and covered 
by a continuous thick, leathery skin which is somewhat cartilaginous at 
the flexible margins of the carapace. Head long and pointed, with a 


176 ILLINOIS BIOLOGICAL MONOGRAPHS 


tubular snout prolonged into a fleshy proboscis with nostrils terminal. 
Fleshy lips concealing the horny coverings of the jaws. The ear is com- 
pletely hidden. Head and neck completely retractile within the shell; 
limbs exposed. Feet large; digits 5-5; claws 3-3, the fourth and fifth 
digits clawless. 

OsTEOLOGICAL CHARACTERS.—Carapace not completely ossified. Outer 
extremities of the nuchal plate overlie the second dorsal rib; the neural 
plates are well developed. The hypoplastron is distinct from the hyoplas- 
tron. Plastron with not more than five callosities. Bony choanae between 
the orbits; postorbital arch narrower than the diameter of the orbit. 
Posterior border of the pterygoids free and without an ascending process. 


Amyda mutica (LeSueur ) 


(Spineless soft-shell; queen turtle; leatherback; soft-shell) 


Trionyx muticus LeSueur 1827 Potamochelys microcephala Gray 1864 
Gymnopus muticus Duméril & Bibron Callinia microcephala Gray 1869 
1835 Aspidonectes muticus Baur 1888 


Amyda mutica Agassiz 1857 


Description.—Body greatly depressed, broadly oval approaching 
circular in outline, covered with a thick, leathery skin and without 
scales, the carapace flexible at the margins, being largely cartilaginous. 
Carapace smooth, occasionally slightly granular. Anterior margin smooth, 
without a trace of the row of tubercles which adorn this region in A. 
spinifera, and other North American members of the genus. The edge 
of the carapace is entire, without serrations. The plastron is placed 
anterior, leaving the posterior limbs exposed and non-retractible within 
the shell. Like the carapace, the plastron is largely cartilaginous. The 
entoplastron has a single callosity, the epiplastra each a small callosity, 
these being best developed in the adult, and better developed in males 
than in females. The head is small, slender, long and pointed, sloping 
rapidly anterior to the eyes into a short, fleshy proboscis. This pro- 
boscis terminates obliquely, so that the nostrils, while terminal, tend to be 
somewhat inferior in position; they are circular and show no trace of 
a ridge projecting into them from the side of the septum. The margins 
of the jaws are slightly concave; the horny covering of the upper jaw 
has a keen cutting edge which is deepest toward the anterior symphysis 
and bluntly toothed toward the posterior articulation. Lower jaw with a 
sharp cutting edge, and both jaws with a narrow alveolar surface. The 
horny covering of the jaws is at least partially concealed beneath the 
fleshy lips. The limbs are well developed, strong; the feet are fully 
webbed with both marginal arid interdigital webbing. The anterior limbs 
have a few transverse scales on their dorsal surface, and the posterior 


THE TURTLES OF ILLINOIS—CAHN 177 


limbs usually have a single larger scale. Digits 5-5, the claws 3-3, the 
two outer digits being concealed in the web and being without claws. 
Tail strong, conical, fleshy, pointed. 

Cotoration.—The dorsal surface of the carapace, head, neck, and 
limbs are brown to olive-brown. The carapace may be unicolored or 
marked with small, obscure blackish spots or blotches, and short, slender 


Pirate 24.—Amyda mutica: A, Adult female, ventral view. B, Adult female, 
dorsal view. C, Newly hatched young, dorsal view. D, Adult, lateral view. E, Head 
study of an adult. 


178 ILLINOIS BIOLOGICAL MONOGRAPHS 


lines. There is a light, yellowish margin to the carapace, this preceded 
mesially by a black line. These markings vary considerably both with 
the individual and with the age of the specimen, becoming obscure in 
fully adult animals. The plastron is pearly white, somewhat translu- 
scent; the under sides of the head, neck, and limbs are whitish and are 
unmarked. Soles of the feet bluish gray, unmottled. A pale, black- 
bordered stripe extends from the snout to the eye, posterior to which it 
is continued along the sides of the neck. 


YounG.—The young resemble the adult in all structural features, but 
differ considerably from them in color pattern. The most frequent 
coloration shows the carapace sprinkled with many fine, bacilliform 
dashes of darker brown on the otherwise unicolored carapace. The 
lateral and posterior margin of the carapace is bordered with yellow, 
this preceded by a black mesial line. With age these bacilliform mark- 
ings seem to spread and tend to become amoeboid in shape and analy 
either become obscure or disappear entirely. 


Sex DIFFERENTIATION.—The tail of the male is much longer than 
that of the female, and projects farther beyond the edge of the carapace. 
The callosities of the male are somewhat more pronounced than are those 
of the female. The female usually has long claws on the hind feet, the 
male long claws on the fore feet. Fully adult males are much smaller 
than similar females. ; 


GrocrapHic DistRiBuTION.—Amyda mutica is found to range from 
the St. Lawrence River southward to Florida, and westward through the 
plains. From the north it is reported by Nash (1906) as very rare for 
the Ontario side of Lake Erie. It is recorded in the fauna of Pennsyl- 
vania by Surface (1908) because of this record of Nash, but no locality 
records are given for that state; it is not listed for New England by 
Babcock (1919). Morse (1904) states definitely that it has not been 
found in Ohio, though Smith (1882) records it from Lake Erie and 
from the Ohio River, which agrees with the range given by Davis and 
Rice (1883) as “north of the Ohio River.” Blatchley (1891) reports it 
from Western Indiana, and Hay (1892) has records extending from 
northwestern to southeastern Indiana, though Evermann and Clark 
(1920) do not record it in Lake Maxinkuckee. The type was collected 
from the Wabash River at New Harmony, Indiana, about due east of 
Carmi, Illinois. Ruthven et al (1928) do not report its occurrence in 
Michigan. For Wisconsin it is reported from the western half of the 
state by Higley (1889), who says it is more common there than is 4. 
Spimfera. Hoy (1883) had previously reported it from “all the tribu- 
taries of the Mississippi River.’”’ In contradistinction to this, Pope and 
Dickinson (1928) refer to the meager records of the species in the state 


THE TURTLES OF ILLINOIS—CAHN 179 


as indicating its presence is “rather unusual.” Over (1923) reports it 
from the Missouri River in South Dakota, but as an uncommon species. 
Burt (1927) records it from northeastern Kansas. Hurter (1911) re- 
ports it from the rivers in Missouri, and Hurter and Strecker (1909) 
mention it from Arkansas, as does Yarrow (1882) who adds a question- 
able Florida record. Blanchard (1922) reports it from western Ten- 
nessee, and the writer has taken many specimens from Reelfoot Lake in 
that region. Halton (1931) does not record it for Alabama, and it is not 
reported from Texas. Ortenburger and Freeman (1930) report it from 
western Oklahoma. 

Itttnots Recorps.—Yarrow (1882) has several records of Amyda 
mutica from Mt. Carmel, Illinois, collected by Ridgway, and an “Illinois” 
record of Kennicott. Davis and Rice (1883) record it from the Missis- 
sippi and “other rivers of the state.’ For the region about Quincy, Gar- 
man (1888) says that A. mutica is abundant in the Mississippi River, and 
less abundant in the sloughs. In his later report (1892) covering 
the state, he reports it from running water throughout the state, 
with specific records from Macki- 
naw Creek in Woodford County, 
Peoria, Quincy, Mt. Carmel (the 
Wabash River; this is close to the 
type locality, New Harmony, In- 
diana), and from the Ohio River 
at Cairo. Hurter (1911) does not 
report it from the Illinois side of 
the Mississippi. Muller (1921) 
reports it from Illinois, across the 


Mississippi River from Freeport, 
Iowa, and records its breeding 
there. The Field Museum has 
specimens from Meredosia and 


from Golconda. The writer has 
examined specimens from the fol- 
lowing localities: Rock Island, 
Meredosia, Havana, Crooked 
Creek in Schuyler County, Robin- 
son, Shawneetown, Carmi, Horse- 
shoe Lake in Alexander County, 
Chester, Murphysboro, Centralia, 
Grafton, Carlysle, Vandalia, Louis- 
ville, Newton, Beardstown, Peters- 
burg, Sterling, and East St. Louis. Map 19.—Amyda mutica. 


180 ILLINOIS BIOLOGICAL MONOGRAPHS 


Hasirat.—The spineless soft-shelled turtle apparently is quite typical 
of rivers and streams in general, irrespective of their size, providing 
these afford a clear bottom of sand or silt. Rock areas are distinctly 
avoided, as are stagnant ponds and overflow areas. Vegetation does not 
attract this turtle as it does most of the hard-shelled species. Current 
means little that is disadvantageous to it, for the great paddle-like feet 
are powerful enough to drive the turtle against a considerable current. 
Since Amyda mutica prefers running water, it is found more often in 
rivers than in lakes. 


Hasits.—As is the case with all of the soft-shelled turtles, A. mutica 
is highly aquatic; it is even more aquatic than A. spinifera for it almost 
never leaves the water and but seldom climbs up on logs to bask in the 
sunshine. On land it seems to feel clumsy and awkward (which in reality 
it is not), and hence never goes far from the edge of the water, except- 
ing perhaps at the breeding season. If one would search for this turtle 
one should seek a river with clear water, considerable current, and a 
sandy bottom free from rocks and plant growth. in such a stream there 
are likely to be windfalls and piles of half-submerged drift-wood along 
the shores, or perhaps a tree lying half on the shore and half in the 
water. About such places one is most likely to encounter A. mutica, for it 
browses around, as it were, among the tangle of brush, seeking food amid 
the partial concealment of the branches of the drift. During the warmest 
days of mid-summer, these turtles sometimes come to the water’s edge, 
and lie upon the flat bank a few inches from the water, as if afraid to 
adventure further inland. Here they bask in the sun, legs drawn up 
under the cover of the drooping edge of the carapace, instantly ready for 
the necessary scramble back into the water. The neck is usually pro- 
truded to the fullest extent, and lies flat on the ground, the turtle being 
fully relaxed. But even though relaxed, the ever-watchful eye is never 
closed, and the turtle is constantly alert for possible dangers. If anything 
suspicious occurs, there is a frantic scramble for the water, the claws 
digging into the soft ground for firmer hold. The progression appears 
awkward, but is surprisingly swift for an animal whose legs are so far 
apart and set so nearly parallel to the ground. Over a level, unobstructed 
sand beach one of these turtles can outrun a man. Once they hit the 
water they disappear beneath the surface with a swirl like that made by a 
fish, as the powerful strokes of their propellers begin to get in their ac- 
tion. These feet are not only very large but are fully webbed, as in all 
of the members of the genus, and give the turtle great speed under water. 

When at rest under water, the turtles select a shallow-water environ- 
ment, free from any vegetation, and here in the sandy bottom they 
proceed to bury themselves. This is done by flipping up the loose sand 
and permitting it to settle down again upon the carapace, until the entire 


THE TURTLES OF ILLINOIS—CAHN 181 


shell is buried from sight and only the head is out. This head, being 
colored so nearly like the sand, is almost invisible. Thus concealed, the 
turtles lie motionless for hours at a time, being able to obtain sufficient 
oxygen for respiration from the water through their pharyngeal method 
of respiration (as will be mentioned in the section dealing with the 
closely related A. spinifera, p. 190). The writer has repeatedly demon- 
strated this pharyngeal respiration in Amyda mutica in the laboratory 
by inserting grains of carmine in the water close to the nostrils and ob- 
serving their sudden dive into the nasal passage as the hyoid apparatus 
drops. A similar phenomenon has also been demonstrated about the 
anus, indicating that there is an anal respiration associated with the pos- 
terior wall of the gut. Some such accessory respiratory mechanism is 
certainly of great advantage to a highly aquatic species of air-breathing 
animal, for the rigid construction of the shell of turtles offers no op- 
portunity for excessive lung expansion or of air storage. Agassiz (1857) 
long ago measured the lung capacity of turtles in relation to their weight 
and in association with their habits. He found that in Amyda ferox, 
which is as aquatic as mutica, the lung capacity was to the body weight 
as 1:17; in Cinosternon pennsylvanicum (K. subrubrum), also exceed- 
ingly aquatic, it was as 1:16; in Cistudo (Terrapene) triunguis, highly 
terrestrial, it was almost as 1:1. Hence it would seem that the aquatic 
turtles have proportionately much less lung capacity than terrestrial 
species. The highly vascular development of the mucous lining of these 
regions, then, enables the turtles to remain under water for long periods, 
and explains their ability to remain so long submerged. It also makes 
clear the method of respiration during the long periods of hibernation 
(and perhaps also of aestivation in some species). The writer has 
demonstrated a similar pharyngeal respiration for various hard-shelled 
turtles as well (Chrysemys, Pseudemys, Sternotherus), and finds that 
the rate of pharyngeal movement increases as the temperature of the 
water rises. While lying, then, concealed in the sand of the river bottom, 
the turtles are able to obtain a sufficient oxygen supply without coming 
to the surface. If they desire more air, they extend their necks upward 
until the nostrils break the surface of the water; hence the selection of a 
shallow-water burial place. This pharyngeal and anal respiration is, 
however, insufficient for the turtles if they are active, which explains 
why soft-shelled turtles die so readily when caught in nets. 

Amyda mutica is an expert swimmer. Very fast, it is able to capture 
fish with ease, its very extensible neck giving it a great advantage in this 
regard. In a large tank I once watched this turtle capture a small brook 
trout (Salvelinus fontinalis fontinalis), one of the fastest and most 
agile of our fish. The turtle approached with great rapidity behind the 
darting fish until its victim was within reach of its snake-like neck; then 


182 ILLINOIS BIOLOGICAL MONOGRAPHS 


there was a lightning-like movement of the head, which shot out like a 
dart, and the trout was caught. Amyda mutica is much less vicious than 
is dmyda spinifera, but its disposition is by no means docile. If cornered, 
it snaps viciously at any offending object, the head shooting forward for 
all the world like that of a snake. It is this fact of relative tempers of 
the two species which has won for the milder mutica the local name 
of “queen” turtle, while its more voracious relative is known as the 
“king” turtle. The edges of the jaws are as keen as a knife, and the 
jaws themselves are powerful enough to inflict a painful injury. 

As already mentioned, A. mutica is a river species. It is able to swim 
against a strong current, and that this is often and consistently done is 
indicated by the fact that, as Garman (1892) has pointed out, it is found 
abundantly below the various dams on the Illinois River, these dams 
impeding possible further progress upstream. If it habitually traveled 
down stream, it would be found abundantly above the dams, where in 
fact it is rare. Since the species is so very aquatic, the dams form 
efficient barriers to its progress. 


NestinG Hasits.—There is little information about the nesting 
habits of this turtle available, and the writer has only once, and then im- 
perfectly, seen the nest digging, which is apparently very similar to that 
of A. spinifera. When leaving the water, the female is extremely cautious 
and very alert for possible danger. The head is held high and the vicinity 
is carefully inspected for possible dangers. The female does not go far 
from the water if suitable nesting grounds are available close by; most 
nests the writer has found have been within fifty feet of the water’s edge. 
Open sand bars in the larger rivers, or the sandy shore of an island free 
of vegetation are most desired, but the turtles come to the mainland if 
no such isolated spot is available. The nest is usually dug in clear sand. 
I have on occasion dug up the eggs of this turtle in very loose sandy 
loam, but never in a tight-packing soil, through which the young could 
not escape. It is believed that the hole is dug with the hind feet, though 
I have never been able to get close enough to this species to be certain of 
the fact, the fore feet remaining in place during the operation. Often- 
times several holes were started, but for some reason best known to the 
digger, each proved unsatisfactory and was abandoned until just the 
right spot was located—sand neither too hard nor too soft, neither too 
wet nor too dry. After laying, the turtle fills in the hole and, with the 
hind feet, rakes sand over the eggs, so as to leave but little trace in the 
disturbed area. Then the female scurries for the water. In the vicinity of 
Meredosia, on the Illinois River, all indications point to early July as the 
nesting season, for after about July 10 no females were secured with eggs 
in the oviducts ready for deposit. 


THE TURTLES OF ILLINOIS—CAHN 183 


Eccs.—The eggs of A. mutica are round and white, and are smaller 
than those of A. spinifera which they so closely resemble. The normal 
number laid by a female is from 18 to 22; the largest number the writer 
has obtained from a single nest is 31, while Muller (1921) reports 33. 
The number of eggs laid is proportional to the size (age) of the female, 
the young individuals laying fewer eggs than the old ones. This accounts 
for clutches of 5 or 6 eggs as are occasionally found. The average size 
of 116 eggs measured by the writer is 22.6 mm, as compared with 28.3 
mm for spinifera. Incubation lasts approximately 70 days and, as pointed 
out by Muller, varies with conditions of heat and moisture; excessive 
moisture kills the embryo, while excessive drought simply retards the 
development. Describing the embryo in the egg, Muller says: ‘The 
carapace is folded down around the young turtle, and the arms are ex- 
tended in front of the head. The forepaws are thrust through the shell 
first in hatching, and this opening enlarged to allow egress for the rest 
of the body. Although the young have an egg tooth below the flexible 
proboscis, it does not seem to be used in escape from the egg, and is 
dropped a week after hatching. They always hatched during the night 
or early morning.” On hatching the young turtle is almost perfectly 
circular, about 34.5 by 33 mm, 


Foop Hasits.—Amyda mutica is distinctly a carnivorous turtle, 
though vegetable matter does play a minor role in the diet. The food con- 
sists principally of crayfish, fish, frogs, tadpoles, the larger insect larvae 
and nymphs, and aquatic mollusks. The fish eaten are for the most part 
minnows, the large shiners Notropis heterolepis heterolepis and N. whip plii 
Spilopterus frequently appearing in stomach examinations; other species 
of fish identified are: Notropis hudsonius selene, Helioperca macroclura, 
Lepibema chrysops, Perca flavescens, Catostomus commersonii com- 
mersonu, Hepentelium nigricans. The mollusks eaten are both gastropods 
and bivalves, the latter being thin-shelled species of small size, but there is 
seldom sufficient evidence of the shell left to afford identification. Over 
(1923) reports “young fowl” as an item of diet; Agassiz (1857) reports 
the larvae of neuropterous insects; Von Wied (1865) reports LeSueur’s 
record of worms, snails, fruits, and even hard nuts; Hay (1892) reports 
this species as very fond of potato stems. It is only to a slight extent a 
scavenger. 


ENemMies.—Great numbers of the eggs of this turtle, as well as of 4. 
Spinifera, are dug out of their sand nests by skunks and raccoons, and 
the empty shells strewn around the ravaged nesting site bespeak a not in- 
considerable havoc wrought by these nocturnal marauders. The adult 
turtle is so capable of caring for itself that it has but few enemies other 
than man himself. One might expect ectoparasites, such as leeches 
(Placobdella parasitica), would find the exposed soft parts of these soft- 


184 ILLINOIS BIOLOGICAL MONOGRAPHS 


shelled turtles an ideal feasting ground, but, since A. mutica, at least, 
shuns vegetation and quiet water where leeches are most abundant, it is 
but seldom attacked by these animals. 

Economic Importance.—Like A. spinifera, mutica is a most palat- 
able turtle and is highly desired for table purposes. It is inferior to 
Spinifera only because of its somewhat smaller size. Despite this fact, 
the soft-shelled turtles are seldom found in the markets of the larger 
cities. Clark and Southall (1920) report: “None was seen in the Wash- 
ington market nor in Chicago, where it was reported that ‘they could not 
be given away, much less sold.’ And yet, where well known, the soft- 
shell is regarded as the most delicious of turtles. It is, indeed, a species 
of soft-shell turtle which is raised in Japan much as the diamond-back 
terrapin is beginning to be raised in this country.” 


Amyda spinifera (LeSueur) 
(Spiny soft-shell; king turtle; leatherback; soft-shell) 


Trionyx spiniferus LeSueur 1827 Trionyx argus Gray 1855 
Trionyx ferox (part) LeConte 1830 Aspidonectes spinifer Agassiz 1857 
Platypeltis spinifera Fitzinger 1835 Gymnopus olivaceus Wied 1865 
Gymnopus spiniferus (part) Duméril & Callinia spinifera Gray 1869 

Bibron 1835 Trionyx spinifer Boulenger 1889 
Trionyx ferox Dekay 1842 Aspidonectes spiniferus Rhoades 1895 
Tyrse argus Gray 1846 Amyda spinifer Hurter 1911 


DescripTion.—Seen from above, the carapace is broadly and bluntly 
ovate. It is covered with a soft, leathery skin, the horny scutes being 
entirely absent. The ossification of the carapace is incomplete, the ribs 
extending beyond the periphery of the costal plates; the marginal plates 
are entirely absent, permitting the edge of the carapace to droop over 
the limbs and head. The shell is greatly depressed, and nearly flat. 
There are no emarginations of any kind, the margin being entire. The 
dorsal surface of the carapace is often finely granular, like fine sandpaper, 
and there is a series of conical tubercles along the anterior margin. The 
plastron is likewise incompletely ossified, the elements being loosely asso- 
ciated and reduced in size. The plastron is anterior in position, its 
anterior margin being in a vertical line with that of the carapace, while 
the posterior limits are only about two-thirds the distance back when 
compared to the carapace. It is so placed as to afford complete protection 
to the withdrawn head, neck, and fore limbs, but none whatsoever to the 
hind limbs and tail, which are at all times fully exposed. The neck is 
extremely long and is capable of extension to nearly three-fourths the 
length of the carapace. The head is small and pointed, the skull de- 
pressed. The snout is prolonged forward into a soft, slender, tube-like 
proboscis with terminal nostrils. These nostrils are concentric, or reni- 


THE TURTLES OF ILLINOIS—CAHN 185 


form, and show a lateral ridge on each side of the nasal septum. The 
jaws are poweriul and possess a sharp cutting edge, but are concealed 
laterally by fleshy lip-like flaps. The limbs are large and powerful, the 
feet large and fully webbed. Digits 5-5; claws 3-3, the three inner digits 
on each foot being supplied with well-developed claws, the remaining 
being without claws and concealed in the webbing. The tail is large and 
fleshy anterior to the anus, and much attenuated posterior to it; it pro- 
jects beyond the edge of the carapace, with the anus close to the tip. 


Pirate 25.—Amyda spinifera: A, Adult male, ventral view. B, Adult male, 
dorsal view. C, Lateral view. D, Young, dorsal view. E, A congenital deformity in 
a sexually mature female. F, Head study of an adult. 


186 ILLINOIS BIOLOGICAL MONOGRAPHS 


CoLorATION.—Carapace olive green or light brown, margined with 
yellow. This margin is widest along the posterior border, becoming 
narrower anteriorly. Between the yellow margin and the body of the 
carapace is an interrupted, wavy black line. The carapace is dotted with 
numerous dark brown spots, those nearest the margin being smallest and 
darkest. Toward the mid-dorsal line these spots become larger and each 
is surrounded with a black ring. The nature of these ocellated spots 
varies greatly with the age of the individual; they are regular and very 
conspicuous in the younger turtles, becoming irregular in outline, larger 
in size, and less bright in mature specimens, finally fading into irregular 
blotches, with little if any symmetry. The plastron and under surface of 
the carapace is immaculate, white, or ivory in color, and the plastral ele- 
ments tend to show through as a purplish discoloration. The head and 
neck are olive. A pale yellow stripe edged with black extends along the 
neck, passing through the eye and on to the snout where, at the tip, it is 
joined by its fellow from the opposite side; a similar stripe extends 
backward from the angle of the jaw. The legs and feet are olive, mottled 
with black, the legs dorsally, the feet both above and below. The anterior 


PLATE 26.—Amyda spinifera: (Left)—An immature individual, six and a half 
inches long, which lacks the typical spotted markings, having instead lichen-like 
patches of dark pigment. (Right)—A typically marked immature individual of 
nearly the same size. 


THE TURTLES OF ILLINOIS—CAHN 187 


limbs bear a series of transverse scales dorsally; the posterior limbs bear 
a single transverse scale. The tail is olive, with a black-bordered yellow 
lateral stripe. 

YounG.—The young resemble the adults in all essential details of 
form and coloration. In the young specimens the ocellate spots are bright, 
regular, and conspicuous, these dimming and becoming irregular in older 
individuals. The granular surface of the carapace is more pronounced in 
the younger specimens. 

Sex DIFFERENTIATION.—The tail of the male is much longer than 
that of the female, and projects farther beyond the posterior edge of the 
carapace; it is also heavier and fleshier. The granular finish of the 
surface of the carapace is more pronounced in the female than in the 
male, and the tubercles on the shield are larger and more numerous on 
the female than on the male. 


GEOGRAPHIC DistRIBUTION.— ‘Mississippi River and tributaries, west 
to Colorado, north to Montana; St. Lawrence River and tributaries ; east 
to Vermont, western New York and Pennsylvania” is the range as given 
by Stejneger and Barbour (1923). Babcock (1919) records the species 
for Vermont from Lake Champlain, the only New England record, and 
Surface (1908) records it from rivers in Pennsylvania. Morse (1904) 
says that it is found in every stream in Ohio, and Ruthven et al (1928) 
report it from the southern half of lower Michigan. Hay (1892) reports 
it as the commonest soft-shelled turtle in Indiana, occurring throughout 
the state; it is interesting to note that the type locality is New Harmony, 
on the Wabash River. Swinging southward we find Blanchard (1922) 
recording it from western Tennessee, where I have found it abundant in 
Reelfoot Lake; Haltom (1931) records it for Alabama. The writer has 
specimens from Louisiana, where Beyer (1900) reports it as abundant 
inland; apparently it does not occur in Florida. It is not recorded from 
Texas, where Strecker (1915) reports only A. ferox and A. emoryi. In 
western Oklahoma only A. mutica is reported by Ortenburger and Free- 
man (1930), and only mutica is recorded from Arkansas by Hurter and 
Strecker (1909). Hurter (1911) reports it from numerous rivers in 
Missouri, and Burt (1927) records that spinifera is more common in 
Kansas than is mutica. Ellis and Henderson (1913) record it as being 
common in Colorado, making no mention of mutica, yet Over (1923) 
reports only mutica from South Dakota. Blanchard (1922) reports 
Spinifera from Iowa. Higley (1889) says it is found in southern and 
western Wisconsin, and Pope and Dickinson (1928) report it as “state- 
wide” in Wisconsin; Cahn (1929) records it from southern Wisconsin. 
To the north Nash (1906) says that it is “distributed in all marshy waters 
of western Ontario, not common anywhere.” 


188 ILLINOIS BIOLOGICAL MONOGRAPHS 


PLATE 27.—Amyda spinifera: (Above)—Study of the surface of the carapace 
to show the highly granular surface. (Below)—Study of the anterior margin of 
the carapace to show the terminal marginal row of tubercles characteristic of the 
species. 


THE TURTLES OF ILLINOIS—CAHN 189 


Ittrnors Recorps.—Amyda spinifera is distributed throughout the 
state of Illinois, and is an abundant species. Davis and Rice (1883) 
record it from Lake Michigan and as abundant in the rivers of the state. 
Garman (1888) reports it as abundant in the Quincy region, and in his 
state report (1892) gives records of it from Rock Creek in Plano County, 
Oregon, Quincy, Peoria, Bluff Lake in Union County, and Mt. Carmel. 
Hankinson (1917) found it in the Embarrass River at Charleston, and 
Weed (1923) reports it from Meredosia. The Field Museum has speci- 
mens from Momence, Jackson Park in Chicago, Havana, Meredosia, and 
Grafton. The writer has exam- 
ined specimens from the follow- 
ing localities: Meredosia, Havana, 
Bureau, Chester, Peoria, Crooked 
Creek in Schuyler County, Rock 
Island, Barstow, Hillsdale, Ster- 
ling, Rockton, Freeport, Belvidere, 
Fox Lake, Decatur, Vandalia, 
Louisville, Chandlerville, Carlin- 
ville, Ellisville, the Kaskaskia 
River at Reilly Lake, and Streator. 


Hapitat.—The spiny _ soft- 
shelled turtle is preéminently a 
shallow-water species, inhabiting 
lakes, ponds, and rivers which 
have a soft sandy or muddy bot- 
tom, and avoiding those waters 
having much current or rock and 
gravel bottoms. It is less depend- 
ent upon aquatic vegetation than 
are other species of pond turtles, 
for it depends upon its ability to 
bury itself in the soft bottom 
when concealment is necessary 
rather than upon hiding among 
aquatic plants. Its swimming 
power enables it to cope with the 
current of even the largest rivers. 

Hasits.—This turtle is exceedingly aquatic, spending by far the 
greater part of its life in the water and leaving this congenial environment 
only for some extraordinary reason and to lay its eggs. In the soft mud 
or sand at the bottom of a shallow lake or river this species buries itself 
with great rapidity by flipping the light silt over its back until it is 


Map 20.—Amyda spinifera. 


190 ILLINOIS BIOLOGICAL MONOGRAPHS 


wholly concealed from view. Usually only the tip of the snout projects 
from the dirt covering. This burial usually takes place in water so 
shallow that the turtle can extend its long neck sufficiently to protrude 
its nostrils enough above the surface to breathe, all this without uncover- 
ing or disturbing its body. Thus it may lie concealed, at rest, for hours. 
The position of the body is always horizontal, and the covering is only 
a thin film of sediment. The ability of these turtles to remain for long 
periods—many hours—beneath the surface without reaching air has been 
demonstrated by Gage (1886), who showed a true aquatic form of 
respiration for both spinifera and mutica. He showed that there is a 
rhythmic movement of the hyoid apparatus at the rate of 16 movements 
per minute. By the raising and lowering of this structure the mouth and 
pharynx are filled with water and then emptied. The mucous membrane 
of the pharynx is highly vascular, the capillaries lying in filamentous 
villi-like processes, and these function as gills. Further, an analysis of 
the water in which the turtle was confined for hours without access to 
air showed that the oxygen supply was greatly depleted and that the 
water contained a large excess of carbonic acid. 

Being thus so highly aquatic, it is not surprising to find this species 
a remarkably fine swimmer, capable of extremely rapid movement. In 
fact the entire creature is adapted to just this type of life, and to a 
higher degree than is found in any other fresh-water turtle. The exces- 
sively depressed body, the thin and flexible cutting edge of the carapace, 
the placing of the limbs in such a position that they propel the animal 
from a point beyond the hindrance of the carapace, the great webbing of 
the feet, all unite in making the soft-shells the fastest moving and most 
agile of our turtles. In swimming, the neck is extended forward in a 
straight line; the limbs strike out horizontally left and right, alternating 
in their action. So great is their speed that they are able to capture the 
fastest of our fishes. Whey they crawl leisurely on the bottom, we find 
the limbs are attached in such a position that only the inner two toes can 
touch the ground, and so buoyant are the turtles that they are incapable of 
rapid walking when submerged. On land their locomotion appears awk- 
ward, yet here they are capable of getting up surprising speed. When 
one is in full retreat you must “‘trot along right smart” if you would keep 
up with it or capture it. 

When disturbed the turtle withdraws within its shell with remark- 
able completeness. Agassiz (1857) thus describes the performance: 
The neck and head are withdrawn entirely within the shield, the skin rolling 
off from the greater part of the neck and allowing it to protrude naked among the 
viscera. The legs are withdrawn horizontally and the skin slips off so far that it 
does not surround them, except below the knees and elbows. When thus with- 


drawn, the humerus is carried round into or before the widespread scapular arch, 
the elbow being placed very near the head or neck; the fore leg and foot are 


THE TURTLES OF ILLINOIS—CAHN 191 


turned back upon the humerus, the flat surface of the foot being nearly horizontal, 
so that its outer edge rests against the femur, and the foot again turned somewhat 
forward, its flat surface being nearly horizontal. 


The long, supple, snake-like neck is a great asset to the turtle in captur- 
ing its prey. So long is the neck that the creature can almost reach your 
fingers when you hold it by its tail. Yet one would never suspect its 
extensibility when the turtle is behaving quietly. Its disposition is pug- 
nacious and irritable and it strikes forward or laterally with lightning 
speed and perfect accuracy. The jaws are powerful and the bite extremely 
painful, for the jaws very easily cut deep into the flesh. 

Amyda spinifera goes into hibernation toward the end of October, 
burying itself to a depth of about two to four inches in the mud or sand 
at the bottom of the lake or river. The burial is accomplished by flick- 
ing at the sand with the feet and permitting it to settle over the carapace. 
It emerges again in May or, if the season is a warm one, toward the end 
of April. In the southern part of the state there is evidence pointing to 
the conclusion that the species does not go into complete hibernation, 
remaining sluggishly active all winter. 

Nestinc Hapsitrs.—As the time for egg laying approaches, this turtle 
shows signs of forsaking its normal aquatic habits and may sometimes 
be seen basking in the sun close to the water’s edge, completely out of 
water. At such times the turtles lie flat upon the plastron, with all four 
legs fully extended and the toes widely spread, completely relaxed. The 
hind feet rest upon the inner toe, the soles directed upward and inward. 
The least disturbance, however, is sufficient to send them plunging back 
into the water and they then show a marked timidity about returning 
to their sun bath. 

When the female comes out to lay, so cautious and alert is she that 
it is almost impossible to observe her activities from a point sufficiently 
close to see what is actually going on. This difficulty Mr. Combs over- 
came by sitting up in a tree for hours at a time, observing the turtles 
through powerful binoculars. The nesting performance is as follows: A 
female about twelve inches long left the water at 11:15 on the morning 
of July 11, 1931. She progressed only about four feet from the water 
when she turned and went back into the river, entering, however, only 
the shallows. A few minutes later she repeated the performance and 
returned again to the water. A third time she came out some five feet up 
stream, at a point where the willow brush was less dense and the sand 
more abundant. She held her neck erect and very stiff, and advanced with 
extreme caution. After traveling 18 feet from the water, a distance 
which it required about 15 minutes to cover, she came to rest and re- 
mained entirely motionless, neck fully extended, for two minutes. Then, 
very deliberately, she planted her fore feet firmly in the sand, and began 


192 ILLINOIS BIOLOGICAL MONOGRAPHS 


scratching slowly with her hind feet. From the time she planted her 
front feet until the eggs were laid and the nest covered, she never moved 
the fore feet from this spot. In digging the hole she made two or three 
slow, heavy scratches with one hind foot; this was followed by a sudden, 
violent kick which sent the dirt flying four or five feet behind her. 
Scratching then began with the opposite foot in exactly the same manner. 
Thus for 16 minutes she dug, alternating in the use of her hind feet, 
every third or fourth stroke shooting out the loose dirt which the pre- 
ceding scratchings had loosened, building up a pile of dirt immediately 
behind her. During all the digging she held her head high, carefully 
watching. 

As soon as the digging ceased, she drew in her neck and remained 
very quiet for 8 minutes, during which time the subsequent examination 
of the nest showed she laid 12 eggs. Then, her front feet still in their 
original position, she began filling in the nest. This she accomplished by 
extending her hind feet backward and raking into the hole the loose sand 
her excavating had piled up. With the front feet acting as a fixed pivot, 
she rotated her body and hind legs through an arc of about 90°, dragging 
in all the loose sand within reach. As soon as this was completed to her 
satisfaction, she wheeled quickly about and without a glance behind her 
at the nest which she never saw, hurried back into the water. 

Then the nest was examined. It was found to consist of a hole 
descending at an angle of about 60°, the opening at the surface lying 
under what was approximately the middle of the plastron while the 
animal was digging. Thus the eggs when laid were deposited upon an 
inclined plane down which, being spherical, they rolled. It could not be 
determined from the point of observation whether or not the hind legs 
were used in lowering the eggs into the hole. A second interesting fact 
was that the sand which surrounded the eggs was very much wetter 
than the surrounding material. From this the obvious conclusion must be 
drawn that the female, as she packed in the sand around the eggs while 
filling up the hole, wetted it down, undoubtedly with water stored in the 
cloacal region. The utilization of water in this manner has been observed 
in the case of other turtles. The sand at the surface was so neatly 
packed down that the nest site was almost invisible. 

As we have mentioned, the eggs are spherical, and each is covered 
with a thick, strong, and rather brittle calcareous shell which is less 
flexible than the shell of many other turtle eggs. In this respect the 
eggs of the family Trionychidae, Chelydridae, and Kinosternidae differ 
from those of all the rest of our inland turtles, though the last-named 
group does not lay spherical eggs. Beneath this shell lies a very tough 
membrane. The shell is pearl white in color, quite smooth and unglazed. 
Agassiz (1857) reports the number of eggs laid as “from twelve to 


THE TURTLES OF ILLINOIS—CAHN 193 


twenty or more,” while Surface (1908) and others report the number as 
“about 60.” I doubt if any A. spinifera lays this number of eggs in a 
season, and assume that the authorities for these high numbers include 
in the count all of the larger eggs found in the ovaries as well as the 
shell-covered eggs about to be laid which are in the horns of the uterus, 
the counts having been made from dissected females rather than from 
dug-out nests. This is obviously unfair, for the larger embryonic eggs 
are retained in situ for laying the following spring. My experience shows 
that the number of eggs laid by females in Illinois is as follows: 9, 12, 
13, 15, 17, 19, 19, 21, 22, 22, 23, 25, with the average of this series as 18. 
The eggs are large, measuring 28.3 mm as the average for 217 eggs, with 
the largest measuring 29.3 mm. An examination of the ovaries inclines 
me to the belief that this species must attain a carapace length of about 
24 cm before the females become sexually mature. 

There are no data available as to the exact duration of incubation 
and no doubt this period, whatever it may be, is varied considerably both 
ways from a mean by climatic and soil conditions: by the type of soil in 
its relation to heat and moisture retention, by temperature and by rain- 
fall which cools off the soil and hence may slow up the rate of develop- 
ment. Most of the Illinois turtles of this species lay in June or early 
July: earlier in the southern part of the state, later in the northern por- 
tion, and young-of-the-year are taken in late August and September. 
Further, there is no information at hand or available dealing with the 
rate of growth after hatching. The only material of this nature to which 
we can refer is offered by Mitsukuri (1905) for Amyda japonica 
(sinensis ?), a closely allied species, as follows: 


Length Width Weight 

Age in cm in cm in gms 
Aittsty hat Ched areata reersveyarsieie = c1eejereresere terete 2.7 25 wae 
ETS CRY Cl Telereein state stotetniie cies cc seas ew 4.5 4.2 23 
Second syeateriesc a ter cenities sues wee 10.5 8.8 169 
MT Ca Tate atetere rs ste eres) a:s/sresineieieteevets 12.2 10.5 300 
Hountheyeaneaeecas esecccsccs se eeiece 16.0 135 563 
IEth years ce cise seas gaesceuccseaceecs 17.5 15.1 750 


Foop Hasits.—Amyda spinifera is conspicuously carnivorous in its 
diet. The commonest items of food found in stomach examinations are: 
crayfish (Cambarus spp.), minnows, fry of larger fish, frogs, tadpoles, 
earthworms, insects (often beetles), and mollusca (Piscidium, Planorbus, 
Vivipara, etc.), in the order named. Sometimes aquatic vegetation is 
found, but this is not common. Among the fish that have been identifiable 
I note: Notropis heterodon, N. heterolepis heterolepis, N. hudsonius 
selene, Catostomus commersonii commersoni, Allotis humilis, Helioperca 
macrochira, Semotilus atromaculatus atromaculatus, Abramis crysoleucas, 


194 ILLINOIS BIOLOGICAL MONOGRAPHS 


Umbra limi, and Aplites salmoides. In Wisconsin I found the remains of 
brook trout (Salvelinus fontinalis fontinalis) six inches long in the stom- 
ach of a 13-inch turtle, attesting the speed and agility of the species in 
capturing its food. It is also a scavenger, picking up a lot of débris from 
the shallow water. 

Economic Importance.—According to Clark and Southall (1920) 
this turtle seldom finds its way into the large market centers of the city 
and certainly it is far more seldom seen there than the snapper. This is 
due no doubt to at least two important factors. First and foremost is the 
fact that the river fishermen who capture these turtles recognize their 
delicious table qualities, and they are disposed of at the local markets near 
the point of capture without the necessity of shipment to distant markets. 
In the second place they are far more delicate than the hardier snapper 
and consequently they do not stand shipment as well. Be that as it may, 
the spiny soft-shell is a delightful table delicacy, the very nature of its 
food supply insuring its meat of a palatable flavor. Along the Illinois, 
Rock, and Mississippi rivers particularly, thousands of pounds of these 
turtles are captured annually and bring a good price on the local markets. 
Hence the species must be regarded as of considerable economic import- 
ance. This fact the state recognizes and has placed a minimum size limit 
of 7 inches on all of the species of soft-shelled turtles. 


TABLE 20.—MEASUREMENTS OF ILLINOIS SPECIMENS OF Amyda_ spinifera 
(Measurements in millimeters) 


: Carapace Plastron Tail 
Specimen 
No. 

- Length Width Length Width Depth Total A-T 
1 Oe eee 168 142 110 55 35 76 8 
Dis ss ecseon es 159 132 119 59 36 tS) 8 
Sige cee 172 149 126 57 34 86 9 
4 adeiendas 176 153 130 61 37 86 10 
Desiecieleciwes 141 119 100 61 29 63 5 
Ole seieyere ayers 124 104 88 39 22 43 5 


HYPOTHETICAL LIST 


After a careful study of the turtles now found within the state of 
Illinois, and a careful review of the literature bearing on all of these 
forms, it has become necessary to designate certain species as hypothetical 
within the state. By this term is meant (1) that the form is no longer to 
be found within the state, if it ever actually did occur there; (2) that it is 
no longer a valid species; or (3) though not taken in the state, its occur- 
rence there is possible. The task of evaluating early records when the 


THE TURTLES OF ILLINOIS—CAHN 195 


original material is no longer available is very difficult at all times; it is 
made more difficult still by the fact that the early investigators did not 
distinguish between subspecies and they did not clearly see the relations 
between closely allied forms in the light in which we do now. There are 
some species reported from Illinois which the writer cannot verify. In 
view of this fact it has been considered advisable to segregate them out 
of the main body of the paper, yet, since they appear in the literature, 
the student is entitled to know what has become of them, and why. In 
this list, then, we attempt to explain why certain forms have been deleted 
from the state list, and to point out certain other species which, for one 
reason or another, may possibly be found within the state by future 
investigators. 

Of the six species placed in this list, three are apparently errors in 
previous identifications: Sternotherus carinatus, Chrysemys picta, and 
Amyda ferox; one is considered as being no longer valid: Chrysemys 
treleasei; one is believed to be of exceedingly doubtful occurrence: 
Pseudemys hieroglyphica; and the remaining species, Clemmys insculpta, 
while never taken in Illinois, has been captured within eleven miles of the 
boundary of the state and hence may be taken in the state at some future 
time. 

Sternotherus carinatus (Gray) 


Aromachelys carinata Gray 1855 Sternotherus carinatus Stejneger 1923 
Goniochelys triquetra Agassiz 1857 Kinosternon carinatum Stejneger & Bar- 
Cinosternum carinatum Boulenger 1889 bour 1917 


DescripTION.—Carapace elongatedly oval, rather narrower at the 
posterior end than at the anterior; very high and massively domed; in 
profile steeper behind than in front. A prominent, sharp keel becomes 
particularly evident on the second vertebral scute, and increasingly prom- 
inent from here backward, the nearly flat sides forming a straight slope 
from keel to marginals. The scales are all highly imbricated; the posterior 
margin of each scute overlaps the anterior margin of the succeeding scute 
as do shingles. The vertebral scutes are all very nearly the same in 
length. The first vertebral is triangular, the apex directed posteriorly, and 
much longer than its anterior width. The second and third vertebrals 
are rhomboidal, their length closely approximating their width. Fourth 
vertebral usually longer than wide; the fifth vertebral is the smallest of 
the series. The median keel arises gradually from the vertebrals and 
appears as a continuous sharp median ridge. The costal scutes are all 
very large, the first being by far the largest of the series. Second and 
third costals highly rectangular; fourth costal irregular in shape. The 
posterior three costals are pentagonal; the anterior roughly rhomboidal. 
Nuchal very small and insignificant. Lateral marginals rectangular; the 
tenth and eleventh (the latter the supracaudalia) are much higher than 


196 ILLINOIS BIOLOGICAL MONOGRAPHS 


PLATE 28.—Sternotherus carinatus: A, Adult, ventral view. B, Adult, dorsal 
view. C, Newly hatched young, ventral view. D, Posterior view of the carapace 
to show the arrangement, relative size and shape of the posterior margina! scutes. 
E, Newly hatched young, dorsal view. F, Adult, lateral view. 


THE TURTLES OF ILLINOIS—CAHN 197 


the rest of the series, the eleventh being higher than the tenth. The 
highest point of the eleventh marginal is toward the anterior margin. 
The -plastron is small, tending toward cruciform, and does not nearly 
close the aperture of the shell. The anterior lobe is truncate along its 
forward border, and is wider than long. The posterior lobe is longer than 
wide, is approximately one-half as wide as the aperture in that region, 
and has a wide, shallow posterior emargination. The front lobe is about 
two-thirds the length of the hind lobe, but longer than the intermediate 
portion. The gular is absent in most specimens, so that the humerals 
form the anterior termination of the plastron. The humerals are roughly 
triangular, the interhumeral suture being shorter than the humeral- 
pectoral suture. Pectorals larger than the humerals, rhomboidal. Ab- 
dominals the largest of the plastral elements. The femorals are much 
longer than wide and tend toward the triangular in general form. The 
anal scutes are rhomboidal, terminating posteriorly in a sharp projecting 
angle, the lateral tip of the posterior emargination. The inguinal and 
axillary elements touch at their proximal ends and form the major part 
of the bridge, completely separating the short wings of the abdominal 
from the marginals. The axillary is triangular and is smaller than the 
rhomboidal inguinal. Head large, massive; snout rather short but 
pointed. The nasal plate is strongly forked. Jaws strong, with sharp 
cutting edges. Gular barbels two; well developed. Legs and feet strong; 
toes webbed. Digits of fore limb all with small claws; fifth digit of the 
hind foot without a claw, and the anterior (first) digit with only a tiny 
one. Fleshy parts posterior to the hind legs covered with small fleshy 
tubercles tending to arrange themselves in lines along the tail. No 
terminal claw or nail present on the tail. 


CoLoRATION.—Carapace varies in color around olive green. Each 
scute is mottled with chocolate brown spots and dashes which sometimes 
tend to extend into radiating lines, the number, conspicuousness, and 
extent of these varying enormously but usually plainly in evidence. The 
posterior margin of each scute, where it overlies the succeeding posterior 
scute, is bordered by a conspicuous but narrow black line. Dorsally the 
marginals bear the same black border along each overlapping suture. 
Plastron is horn color to yellowish, unmarked in most specimens, but 
occasionally exhibiting a very few short brown dashes. There is a large 
amount of cartilaginous material along the interabdominal, pectoral- 
abdominal, and interfemoral sutures, the amount varying with the sex 
of the animal. This material is usually pinkish in color. Head olive, 
covered with numerous small, dark brown flecks and spots both dorsally 
and laterally; there is no stripe back of the eye. Neck and chin pinkish 
gray, also spotted, the spots lacking ventrally. Jaws horn color, with 


198 ILLINOIS BIOLOGICAL MONOGRAPHS 


transverse brown stripes, which are sometimes very faint. The rest of the 
soft parts are grayish in tone and without markings. 

Younc.—The young resemble very closely indeed the young of equal 
size of Sternotherus odoratus, and might well be very confusing. In the 
young specimens there is usually a keel in evidence on both series of 
costal scutes, this keel becoming more and more obscure with age. The 
young S. carinatus lack the light stripes so conspicuous below and behind 
the eye in young and adult S. odoratus. 

Sex DrrrereNTIATION.—In the male the “stridulating organs” are 
well developed on the hind legs as a series of scale-like roughenings. 
Usually the transverse brown stripes on the jaws are much more intense 
in the males than in the females. The amount of cartilage between the 
plastral elements is much greater in the males than in the females. 

GEOGRAPHICAL DIstTRIBUTION.—Sternotherus carinatus is distinctly a 
southern species. It inhabits the lower part of the Mississippi River 
Valley, the range covering Georgia, Mississippi, Florida, Louisiana, and 
westward to about the eastern third of Texas. 

Ittinots Recorps.—The only record of this species for Illinois is to 
be found in the list of Davis and Rice (1883) who state simply: “Has 
been taken as far north as Lake County.” This Illinois record is taken 
seriously by Hay (1892) who quotes it in view of the possibility of 
finding the species in Indiana. Again, Garman (1896) quotes the same 
record and includes the species in his herpetological report of Illinois, 
mentioning, however, that he has not taken it in the state, and putting 
the responsibility for the record upon Davis and Rice. In view of the fact 
that a careful combing of the state during the last three years has 
brought to light not the slightest trace of the species, and because of 
the great distance which Lake County, Illinois, lies north of its known 
range, the present writer rejects it from the Illinois fauna. Yet, in view 
of the case of Kinosternon flavescens, he does so gently but firmly, and 
places it in the hypothetical list until positive evidence in the form of a 
specimen taken in the state comes to hand. The Davis and Rice material 
is not available for study. The writer is inclined to follow Siebenrock 
(1907, p. 552), who believes that Davis and Rice (he quotes, however, 
only the Garman citation) had Sternotherus odoratus and not S. 
carinatus. In view of the tendency of S. odoratus toward keels in the 
immature stages, this seems altogether likely. 

Since the present writer is quite confident that Sternotherus carinatus 
does not occur in Illinois, and that the only published record for it within 
the state is in error, a further discussion of the species will be omitted. 
To those who are interested in the taxonomy of this species and of 
Sternotherus minor with which it has been badly confused, reference is 
made here to a paper by Stejneger (1906). 


THE TURTLES OF ILLINOIS—CAHN 199 


Chrysemys picta Schneider 


Testudo picta Schneider 1783 Chrysemys picta Gray 1856 
Testudo cinerea Schneider 1792 Clemmys picta Strauch 1862 
Emys picta Schweigger 1814 Chrysemys picta picta Bishop and 
Terrapene picta Bonaparte 1830 Schmidt 1931 


The last authority, in point of time, to include this eastern species in 
a list of the turtles of the state is Garman (1892), who says as follows: 
“Under the name of C. picta, this and the closely allied C. marginata are 
included by good authorities as varieties of one species, and as the 
former name has the right of priority, it has come to be commonly applied 
by students to the individuals of the genus taken in Illinois. It is prob- 
able, however, that C. picta will be found to be very rare in this State, 
if it occurs at all.” He gives one locality record. Previous to the Garman 
list, it had been included in the Cook County, Illinois, list by Kennicott 
(1855), in which list the author says that it is “very abundant; exists 
throughout the state.” However, previous to this time the validity of 
these two species (picta and marginata) was not understood, as Garman 
indicates, and when Kennicott reports picta as an abundant species there 
can be little doubt but that he referred to what we now understand as 
marginata, believing that picta and marginata were one and the same 
species. Garman refers to a specimen taken at Mt. Carmel, Illinois, prob- 
ably using as his data the published record of this specimen in the 
Yarrow (1882) list. This record shows U. S. National Museum specimen 
#9559 to be Chrysemys picta, taken in 1878 by Shenck. The writer 
wrote to Dr. Stejneger in regard to this record, and through his kindness 
has learned that the specimen referred to under this number by Yarrow 
is in reality Chrysemys marginata. Hence the Yarrow record is elimin- 
ated, as is also the Garman record. The distribution of Chrysemys picta 
is given by Stejneger and Barbour (1933) as follows: “Eastern North 
America from New Brunswick to Florida.” 


Amyda ferox (Schneider) 


Testudo ferox Schneider 1783 Platypeltis ferox Agassiz 1857 
Testudo verrucosa Schoepff 1792 Gymnopus spiniferus Wied 1865 
Testudo bartrami Daudin 1802 Platypeltis agassiz Baur 1888 
Trionyx carinatus Geoffroy 1809 Trionyx ferox Boulenger 1889 
Trionyx georgicus Geoffroy 1809 Trionyx agassiz Baur 1893 
Trionyx brongnartii Schweigger 1814 Aspidonectes agassiz Baur 1893 
Amyda ferox Oken 1816 Pelodiscus agassiz Baur 1893 
Gymnopus spiniferus (part) Duméril Trionyx agassiztt Hay 1892 


& Bibron 1835 


This southern soft-shelled turtle has been recorded but once for Illi- 
nois, and it is extremely doubtful whether it occurs within the state. This 
Illinois record is that of Kennicott (1855), who records this species as 


200 ILLINOIS BIOLOGICAL MONOGRAPHS 


“common in Lake Michigan and throughout the State.” There can be 
little doubt but that Kennicott is in error here, for he makes no mention 
in his list of the turtles of Cook County of either spinifera or mutica; 
hence we must assume that he did not distinguish between the various 
species of the soft-shelled turtle. And if this is the case, we cannot 
possibly accept his identification of ferox as the common species of IIli- 
nois. Again, Yarrow (1882) records a specimen (48359) in the National 
Museum, from Madison, Indiana, and this record constitutes the sole 
basis for the inclusion of this species in the list of turtles of Indiana as 
published by Hay (1892) under the name Trionyx agassizii. As to 
including it in the hypothetical list of Illinois: outside of the Kennicott 
record the only justification is to be found in the fact that Madison, Indi- 
ana, is on the Ohio River. Since Amyda ferox is, like the other species 
of the genus a highly aquatic species, and since it is a southern turtle, 
the most plausible route this specimen could have taken would be up the 
Mississippi to the mouth of the Ohio, and up the Ohio to Madison, Indi- 
ana. Hence, if the Indiana record is correct, it is just possible that 
sometime a stray specimen may again attempt a similar journey and be 
taken en route in southern or southeastern Illinois. 


Chrysemys treleaser Hurter 


Chrysemys treleasei Hurter 1911 
Chrysemys marginata treleasei Stejneger & Barbour 1917 

This species was described by Hurter in 1911 from specimens taken 
by him in Madison, St. Clair, and Monroe counties along the Mississippi 
River in Illinois. The description of the form is similar to that of the 
other species of the genus (marginata, bellii), and the basis for the found- 
ing of a new species lies in the coloration of the plastron. “The plastron 
is uniformly blood red in the adults, which color partly fades away in 
alcoholic specimens. When the red has faded the plastron sometimes 
shows a faint long and wide blackish mark. In the young of the first 
year the red plastron is divided into squarish fields by the proportion- 
ately wide yellow sutures.” Bishop and Schmidt (1931), in reviewing 
the status of treleasei, give as their opinion that the red color of the 
plastron is due to a superficial deposit of inorganic red pigment (an oxide 
of iron), and point out that this is true of specimens in the Field Museum 
from the same locality which likewise show the red plastron. They fur- 
ther point out that the yellow sutures of the young individuals repre- 
sent new growth of the horny shields, on which the superficial red 
deposit has as yet had insufficient time to become deposited. The writer 
has examined two specimens from Monroe county which were typical 
of Hurter’s description of treleasei, and in both cases scraping with a 
knife revealed the red color of the plastron to be merely a superficial 


THE TURTLES OF ILLINOIS—CAHN 201 


deposit, with the normal yellow color underlying it. Hurter’s statement 
that, on fading, the plastron sometimes “shows a faint long and wide 
blackish mark” indicates the true bellii affinities of the specimens he 
describes as treleasei. Those specimens examined by the writer were 
typical bellii when the red deposit had been removed. Bishop and 
Schmidt accordingly place Chrysemys treleasei Hurter as a synonym of 
Chrysemys picta bellii. With this view the present writer is quite in 
accord. Stejneger and Barbour (1933) have likewise placed treleasei in 
synonymy with bellii. Hence Chrysemys treleasei is deleted from the list 
of species found in Illinois on the ground of being an invalid species. 


Pseudemys Iieroglyphica (Holbrook) 


Emys hieroglyphica Holbrook 1836 Chrysemys hieroglyphica Boulenger 1889 
Ptychemys hieroglyphica Agassiz 1857 Pseudemys hieroglyphica Garman 1892 
Clemmys hieroglyphica Strauch 1865 Pseudemys elonae Brimley 1928 (?) 


The following description is taken from Hay (1892): “Head unusu- 
ally small; snout somewhat projecting; upper jaw slightly notched in 
front; both upper and lower jaws smooth or slightly denticulated. Shell 
greatly depressed, and in large specimens without trace of keel. In 
specimens five inches long there is a slight keel. Shell sometimes smooth, 
occasionally longitudinally wrinkled. At its border, especially behind the 
thighs, the shell flares outward excessively, in some cases producing an 
actual concavity in the shell above. Hinder margin deeply serrated. The 
bridge is narrow from front to back, the width being contained in the 
length of the plastron about three times or more. It rises little toward the 
carapace, and this contributes to the apparent flatness of the shell. Hinder 
border of the plastron with a deep notch. Longest suture that between 
the abdominals; the shortest, that between the humerals. Digits all 
strongly webbed. Hind feet very large and flat. 

“The ground color of the carapace varies from olive to dark brown. 
This is variegated with numerous lines and stripes of yellow. On the 
vertebrals the lines tend to run longitudinally. On the costals broad yel- 
low bands divide each scute into three or four areas, inside of each of 
which are narrow concentric lines of the same color. The marginals are 
marked with yellow and brown. The plastron is yellow, with some 
splotches of brown on the bridge. The head, neck, feet, and tail are all 
dark green, with numerous longitudinal bands of yellow. The length of 
the shell of large specimens is 12 inches.’’ Baur (1893) characterizes 
hieroglyphica by its elongated, narrow shell and its very small head; by 
the presence of yellow stripes and dots on the head which are much 
more distinct than in P. concinna, which it most nearly resembles. 

The only records, apparently, for the occurrence of this species in 
Illinois are those of Garman (1892) and Hay (1892). Garman gives no 
locality records of any kind, and no mention is made of a single speci- 


202 ILLINOIS BIOLOGICAL MONOGRAPHS 


men having been taken or examined by him in Illinois. He merely says: 
“The species has been observed only in the Wabash River.” For a turtle 
so nearly resembling another species (P. concinna), this can hardly be 
accepted as a record or as a proof of its occurrence in the state. Turning 
to Hay, we find little satisfactory information. He says: “Two shells of 
this species are in the State collection, which were sent in from Mt. 
Carmel, Illinois, on the Wabash River. No doubt it will be found along 
the whole lower course of the Wabash.” The writer has been unable to 
locate these two “‘shells’’; correspondence with Mr. Verne Patty, the 
curator of this museum, indicates that if the turtles are still in this 
museum they are packed up and hence not available for study. So we 
must simply take Hay’s statement and weigh it. In the first place, one 
would like to know what is meant by “shells.” Presumably carapace and 
plastron. If so, one would like to know whether the coloration and 
scutellation was sufficiertly distinct to distinguish it from the very closely 
similar P. concinna. Is one to assume that by referring to “shells” Dr. 
Hay wished to designate that no skull was present? Yet the best diag- 
nostic feature to distinguish /ieroglyphica from concinna is the smooth 
cutting edge of both jaws in hieroglyphica and the serrate edge of the 
lower jaw of concinna. Finally, Dr. Hay’s prediction that the species 
would “no doubt” be found along the “whole lower course of the Wa- 
bash” has not been verified during the last forty-one years, for no further 
specimens have come to light. The writer has taken P. concinna from 
this Mt. Carmel region, but an especially vigorous search for P. hiero- 
glyphica in that locality has yielded nothing. Stejneger and Barbour 
(1933) give the range of hieroglyphica as “the rivers of the southern 
Appalachians.” Hence it would appear that Illinois is very far from the 
normal range of the species. There is in the Field Museum a specimen 
of this species (36300), bearing the data: “Kankakee river at Kanka- 
kee.” Correspondence from Dr. Karl P. Schmidt, of the Field Museum, 
states in regard to this specimen: “The Pseudemys hieroglyphica appears 
to be correctly identified, but the locality is quite untrustworthy as 
it is an aquarium specimen received from F. S. Young, but not col- 
lected by him. Any statement of this record should carry this notation. 
The occurrence of this turtle in the Kankakee requires confirmation.” 
The only other nearby record is that of Levette (1876), who reports it, 
strangely enough, from the Kankakee River in northern Indiana! There- 
fore, since the writer has been unable to verify these old records, and 
since he has been unable to obtain a single specimen from the state, he 
feels that the species should be placed in the hypothetical list. If these 
old records are ever verified, and if in the meantime no new specimens are 
obtained, we may then assume that Pseudemys hieroglyphica has been 
exterminated within the state. 


THE TURTLES OF ILLINOIS—CAHN 203 


Clemmys insculpta (LeConte) 
(Wood turtle) 


Testudo insculpta LeConte 1830 Geoclemmys pulchella Gray 1865 
Emys speciosa Gray 1831 Glyptemys insculpta Agassiz 1857 
Emys insculpta Harlan 1835 Glyptemys pulchella Gray 1870 
Clemmys insculpta Fitzinger 1835 Chelopus insculptus Cope 1875 


DescripTIon.—Carapace ovate, approaching retangular, widest pos- 
teriorly across the eighth marginal scutes; depressed; flattened dorsally ; 
serrate posteriorly. Scutes of the carapace very rough, sculptured. First 
and fifth vertebral with length and width about equal; remaining ver- 
tebrals wider than long and of almost identical size and proportions. 
First and second costals the largest of the series but only slightly larger 
than the third; fourth costal the smallest of the scutes of the carapace. 
Marginals vary in number, but usually show 24 plus the nuchal. (For a 
study of this variation, see Parker 1901). Nuchal elongate, narrow, 
deeply notched posteriorly where the anterior margin of the first vertebral 
projects sharply into it. Marginals all flaring, lying almost horizontal in 
position. Each scute of the carapace bears toward its posterior margin a 
“focal point,” from which a few weak ridges radiate. From each focal 
point a series of fine, raised, concentric ridges radiate toward the margin 
of the scute, giving the shel! a highly sculptured surface. The focal 
points on the vertebral and costal scutes are raised and form the apex 
of a flattened pyramid. A weak longitudinal keel is present on the 
vertebrals, most developed posteriorly. Plastron ovate, flat. Gulars 
triangular, their anterior lateral margins projecting into a blunt, rounded 
knob, their anterior margins rounded and emarginate. Anals trapezial, 
with a deep notch between them, the posterior angles rounded. Anterior 
margin of the anals less than the posterior margin of the femorals; 
hence the posterior lateral angle of the femorals forms a rounded pro- 
truding angle ; posterior margin of the femorals deeply concave. Anterior 
lateral angle of the femorals extends into the posterior lateral margin of 
the abdominals, which ‘‘flows” around it to form the base of the bridge. 
Each scute of the plastron with a posterior lateral focal point which is, 
however, not raised, and with a series of concentric angular rugae ex- 
tending from it. Axillary and inguinal elements small, the axillary tri- 
angular. Head flat or slightly dished dorsally, compressed, wider above 
than below; upper jaw projecting downward like a bill and notched at the 
tip. Edge of lower jaw straight except at the tip, which is highly arched 
upward. Alveolar surface of both jaws narrow. Soft parts (except 
head) covered with rough scales or blunt, wart-like protuberances. 

CoLoraTIon.—Carapace a dull brown, with very faint yellow and 
black radiating and concentric lines which become very obscure in adult 
individuals. Plastron yellow, with a squarish black blot on the posterior 


204 ILLINOIS BIOLOGICAL MONOGRAPHS 


lateral margin of each scute except the gulars, on which the spot is 
anterior lateral. Dorsal surface of the gulars yellow, with black anterior 


area. Ventral marginals yellow, with a black posterior lateral blotch. 


PLate 29.—Clemmys insculpta; A, Adult, ventral view. B, Adult, dorsal view. 
C, Adult, lateral view. D, Head study of an adult. This specimen is from Wiscon- 


sin, close to the Illinois state line. 


THE TURTLES OF ILLINOIS—CAHN 205 


Soft parts yellow, orange, or red, with the dorsal surfaces dark olive 
green. Top of head and neck dark olive, blending into yellow on the 
sides of the neck. 


Pirate 30.—Turtle Eggs: The Round Eggs. 4, Amyda mutica. B, Amyda 
spinifera. C, Chelydra serpentina. D, Left to right, to show relative sizes: Amyda 
mutica, Amyda spinifera, Chelydra serpentina, Macrochelys temminckit. (The last 
specimen is the original Agassiz specimen, loaned by the Museum of Comparative 
Zoology.) 


ILLINOIS BIOLOGICAL MONOGRAPHS 


206 


B, Kinosternon 
E. Ter- 
jal 


es: The Ovate Eggs. A, Emys blandingtt 

. Clemmys guttata. D, Sternotherus odoratus. 
G, Terrapene carolina carolina. 

K, 


subrubrum subrubrum. C 
’, Chrysemys picta dorsalis 
I, Chrysemys picta marginata. J, Chrysemys picta bellu 
geographica. 


PLATE 31.—Turtle Eggs: 


FF, 


Pseudemys concinna 
Graptemys pseudogeographica 


M, Pseudemys troostit 


rapene ornata 
pseudogeographica, L, Graptemys 


THE TURTLES OF ILLINOIS—CAHN 207 


Sex DIFFERENTIATION.—In the male the tail is longer than in the 
female; the scales on the front legs are coarser and the claws are heavier 
than in the females. In the adult male the central area of the plastron is 
concave; in the female this region is either flat or slightly convex, as 
it is in immature specimens of both sexes. 

The wood turtle has never been recorded from Illinois so far as 
the writer is aware. It is a northern species, which extends in distribution 
from Maine to Virginia in the east and south, westward to Michigan and 
Wisconsin and northward into Canada. Ruthven, Thompson, and Gaige 
(1928) record it from the northern half of southern Michigan. In Wis- 
consin it is not reported by either Hoy (1883) or Higley (1889), but 
Pope and Dickinson (1928) report it as “probably state-wide” in dis- 
tribution, with records from Shawano County (northeastern Wisconsin), 
Polk County (northwestern), Waupaca County (east central), the upper 
Wisconsin River (north central), and Waukesha County (extreme south 
central). It is included in this hypothetical list of Illinois species only on 
the basis of a specimen taken in the summer of 1933 in Rock County, 
Wisconsin, by Mr. C. R. Naeser, who presented the specimen to the 
writer. This turtle was taken from the Rock River south of Janesville, 
Wisconsin, eleven miles north of the Illinois state line, and is probably a 
transport. While Clemmys insculpta is undoubtedly very rare in southern 
Wisconsin, if it occurs there at all, the capture of a typical specimen so 
close to the Illinois line would indicate at least the possibility of its 
eventually being found in this state. It is one of the very few species that 
future investigators may perhaps add to the list of native Illinois species. 


208 ILLINOIS BIOLOGICAL MONOGRAPHS 


BIBLIOGRAPHY 


ILLINOIS REFERENCES 
Baker, F. C. 

1930. The Use of Animal Life by the Moundbuilding Indians of Illinois. 

Trans. Ill. St. Acad. Sci., XXII:41-64. 
BisHop, S. C., and Scumipt, F. J. W. 

1931. The Painted Turtles of the Genus Chrysemys. Field Mus. Nat. Hist., 

Zool. Ser., XVIII:123-139. 
BLANCHARD, F. N. 

1924. A Collection of Amphibians and Reptiles from Southeastern Missouri 
and Southern Illinois. Papers Mich. Acad. Sci., Arts, and Letters, 
1V:533-541. 

Cann, A. R. 
1931. Kinosternon flavescens, a Surprising Turtle Record from Illinois. Copeia, 
1931: 120-132. 
Caun, A. R., and Conner, E. 
1932. Mating of Box Turtles. Copeia, 1932:86-88. 
Crark, H. W., and SoutHALt, J. B. 
1920, Fresh-water Turtles: A Source of Meat Supply. U. S. Bur. Fish., Doc. 


889 : 3-20. 
Corr, E. D. 
1875. Check-list of North American Batrachia and Reptilia. U. S. Nat. Mus. 
Bull., I: 1-104. 


Davis, N. S., and Rice, F. L. 
1883a. North American Batrachia and Reptilia Found East of the Mississippi 
River. Bull. Ill. St. Lab. Nat. Hist., 1:5:3-64. 
1883b. List of the Batrachia and Reptilia of Illinois. Bull. Chicago Acad. Sci., 
1:25-32. 
EvERMANN, B. W., and Crark, H. W. 
1930. The Painted Box Turtle, Terrapene ornata, in Indiana. Copeia, 1930: 
40-41. 
GaicE, H. T. 
1914. A List of the Amphibians and Reptiles Observed in Richland County, 
Illinois, in May, 1913. Copeia, 1914:11. 
GarMAN, H. 
1889. A Preliminary Report on the Animals of the Waters of the Mississippi 
Bottoms, Near Quincy, Illinois in August, 1888. Bull. Ill. St. Lab. 
Nat. Hist., III:123-184. 
1890. Notes on Illinois Reptiles and Amphibians, Including Several Species 
not before Recorded from the Northern States. Bull. Ill. St. Lab. 
Nat. Hist., I1I:185-190. 
1892. A Synopsis of the Reptiles and Amphibians of Illinois. Bull. Ill. St. Lab. 
Nat. Hist., II1:215-385. 
GaRMAN, S. 
1884. The North American Reptiles and Batrachians. Bull. Essex Inst, 
XVI:3-64. 
Hankinson, T. L. 
1915. The Vertebrate Life of Certain Prairie and Forest Regions Near 
Charleston, Illinois. Bull. Ill. St. Lab. Nat. Hist., X1:281-303. 
1917. Amphibians and Reptiles of the Charleston Region. Trans. Ill. Acad. 
Sci., X:322-328,. 


THE TURTLES OF ILLINOIS—CAHN 209 


Hay, O. P. 
1892. The Batrachians and Reptiles of the State of Indiana. An. Rept. Dept. 
Geol. Nat. Res. Indiana, 17:409-602. 
1911. Herpetology of Missouri. Trans. Acad. Sci. St. Louis, XX:59-274. 
KENNIcorTrT, R. 
1855. Catalogue of Animals Observed in Cook County, Illinois. Trans. Ill. St. 
Agr. Soc., 1:577. 
Korom, C. A. 
1903. Plankton of the Illinois River. Bull. Ill. St. Lab. Nat. Hist., VI :562. 
McLarn, R. B. 
1889. Notes on a Collection of Reptiles from Ft. Smith, Arkansas, with 
Remarks on other Eastern Reptiles. Wheeling, W. Virginia. 
MULLER, J. F. 
1921. Notes on the Habits of the Soft-shelled Turtle, Amyda mutica. Am. 
Midland Nat., VII:6. 
STEJNEGER, L. 
1923. Rehabilitation of a Hitherto Overlooked Species of Musk Turtle of the 
Southern States. Proc. U. S. Nat. Mus., 62:6. 
STEJNEGER, L., and Barsour, T. 
1917, 1923, 1933. Check List of North American Amphibians and Reptiles. 
Harvard University Press. 
Taytor, W. E. 
1895. The Box Tortoises of North America. Proc. U. S. Nat. Mus., XVIII: 
573-588. 
VANCLEAVE, H. J. 
1931. Some of the Biological Effects of Drought. Sci. Monthly, XX XIITI:301. 
Vestal, A. G. 
1913. An Associational Study of Illinois Sand Prairie. Bull. Ill. St. Lab. Nat. 
Hist., X:1:1-96. 
Weep, A. C. 
1922. Reptile Notes. Copeia, 1922:112. 
1923. Notes on Reptiles and Batrachians of Central Illinois. Copeia, 116:45-50. 
Yarrow, H. C. 
1882. Check-list of North American Reptiles and Batrachia. Bull. U. S. Nat. 
Mus., 24:1-249. 


GENERAL REFERENCES 


The following are particularly valuable to the student of turtles, but though 
quoted do not contain references directly to Illinois. 
Acassiz, L. 

1857. Contributions to the Natural History of the United States, I-II. Boston. 
Bascock, H. L. 

1919. The Turtles of New England. Monog. Boston Nat. Hist. Soc., VIII: 

327-431. (Fine colored plates). 
1933. The Eastern Limit of the Range of Chrysemys picta marginata. Copeia, 


2:101. 
Baur, G. 
1887. Ueber die Stellung der Trionychidae zu den ubrigen Testudinata. Zool. 
Anz., X:96. 


1890. On the Classification of the Testudinata. Am. Nat., XXIV:530-536. 
1891. American Box Tortoises. Science, (1) XVII:426:190-191. 


210 ILLINOIS BIOLOGICAL MONOGRAPHS 


1893a. Notes on the Classification of the Cryptodira. Am Nat., XX VII:319. 
1893b. Further Notes on American Box Tortoises. Am. Nat., XXVII:677. 
1893c. Notes on the American Trionychidae. Am. Nat., XX VII:1121. 
BLAKE, S, F. 
1921. Sexual Differences in Coloration in the Spotted Turtle, Clemmys guttata. 
Proc. U. S. Nat. Mus., 59:463-470. 
BouLeENGER, G. A, 
1889. Catalogue of the Chelonians, Rynchocephalians, and Crocodiles in the 
British Museum. London. 
BriM-ey, C. S. 
1903. Notes on the Reproduction of Certain Reptiles. Am. Nat., XXXVII: 
261-266. 
1904. The Box Tortoises of Southeastern North America, Journ. Elisha 
Mitchell Sci. Soc., XX:1:27-34. 
1907. Notes on Some Turtles of the Genus Pseudemys. Journ. Elisha Mitchell 
Sci. Soc., X XIII:76-84. 
Burt, C. E. 
1927. An Annotated List of the Amphibians and Reptiles of Riley County, 
Kansas. Occ. Papers Mus. Zool., Univ. Mich., 189. 
Burt, C. E., and Burt, M. D. 
1929. Field Notes and Locality Records on a Collection of Amphibians and 
Reptiles Chiefly from the Western Half of the United States. Journ. 
Wash. Acad. Sci., XIX :20:448. 
Coker, R. E. 
1910. Diversity in the Scutes of Chelonia. Journ. Morph., XX1:43-44. 
Davis, W. T. 
1887, Color of the Eyes as a Sexual Characteristic in Cistudo carolina. Am, 
Nat., XX1:88. 
DeSora, C. R. 
1931. The Turtles of the Northeastern States. Bull. N. Y. Zool. Soc., XXIV: 
5:131-160. 
Ditmars, R. I. 
1908. The Reptile Book. 
EIGENMANN, C. H. 
1896. The Inhabitants of Turkey Lake (Indiana). Testudinata. Proc. Ind. 
Acad. Sci., V:262. 
Extis, M. M., and HENpERSON, J. 
1913. The Amphibians and Reptiles of Colorado, University of Colorado 
Studies, 10:39-129. 
ENGELHARDT, G. P. 
1916. Burrowing Habits of the Box Turtle. Copeia, 31:42. 
EVERMANN, B. W., and CLark, H. W. 
1920. Lake Maxinkuckee. Indiana Dept. Conserv., Vol. I. 
Ewine, H. E. 
1933. Reproduction in the Eastern Box Turtle Terrapene carolina carolina. 
Copeia, 1933:95. 
Gapow, H. 
1901. Amphibia and Reptiles. Cambr. Nat. Hist., VIII. 
Gace, S. H. 
1884. Pharyngeal Respiration in the Soft-shelled Turtle (Aspidonectes spini- 
fer). Proc. Am. Assoc. Adv. Sci., XX XII:316. 


THE TURTLES OF ILLINOIS—CAHN 211 


Gace, S. H., and Gace, S. P. 
1886. A Contribution to the Physiology of Respiration in Vertebrates. Pro. 
Am. Assoc. Adv. Sci., XXXIV:316. 
GarMAN, H. 
1890. The Differences Between the Geographic Turtles. Bull. Essex Inst., 
XII: 1-14. 
GoopricH, E. S. 
1930. Studies on the Structure and Development of Vertebrates. New York. 
HALLowELL, E. 
1856. [Remarks on living Sternotherus.] Proc. Acad. Nat. Sci. Phil. VII: 
106-108. 
Hattom, W. L. 
1931. Alabama Reptiles. Geol. Surv. Ala., Mus. Paper XL. 
Hay, O. P. 
1891. Some Observations on the Turtles of the Genus Malaclemys. Proc. Ind. 
Acad. Sci., 120-126. 
1903. On the Existing Genera of the Trionychidae. Proc. Am. Phil. Soc., 
XLII: 268. 
Hotsrook, J. E. 
1838. North American Herpetology. Ed. I, Vol. 3. 
Jorpan, D. S. 
1929. Manual of the Vertebrate Animals... . 13th ed. 
LaTHAM, R. 
1916. Notes on Cistudo carolina from Orient, Long Island. Copeia, 34:64-67. 
Levette, G. M. 
1876. The Lakes of Northern Indiana. 7th An. Rept. Geol. Surv. Indiana. 
LoENNBERG, E. 
1894. Notes on Reptiles and Batrachians Collected in Florida in 1892 and 
1893. Proc. U. S. Nat. Mus., XVII:317. 
Loatrr, E. B. S. 
1928. The Amphibians and Reptiles of the Lake Nipigon Region. Trans. Roy. 
Can. Inst., XV1I:290. 
Mitsukur!, K. 
1905. The Cultivation of Marine and Fresh-water Animals in Japan. Bull. 
U.S. Bur. Fish. for 1904, XXIV :259-290. 
Nasu, C. W. 
1906. Batrachians and Reptiles of Ontario. Dept. Educ., Toronto. 
Nertinc, M. G. 
1932. Blanding’s Turtle, Emys blandingii, in Pennsylvania. Copeia, 1932:173. 
Newman, H. H. 
1906. The Habits of Certain Tortoises. Journ. Comp. Neur. and Psych., 
XVI:126-152. 
Nicuots, J. T. 
1933. Further Notes on Painted Turtles. Copeia, 1:41. 
OrtenBurcer, A. I., and FREEMAN, B. 
1930. Notes on Some Reptiles and Amphibians from Western Oklahoma. 
Pub. Univ. Okla., Biol. Surv., I1:175-188. 
Over, W. H. 
1923. Amphibians and Reptiles of South Dakota. S. D. Geol. and Nat. Hist. 
Surv., Bull. 12. 
Overton, F. 
1916. Aquatic Habits of the Box Turtle. Copeia, 26:4. 


212 ILLINOIS BIOLOGICAL MONOGRAPHS 


ParKER, G. H. 
1901. Correlated Abnormalities in the Scutes and Bony Plates of the Carapace 
of the Sculptured Tortoise. Am. Nat., XXXV:17. 
Patcu, C. L. 
1925. Graptemys geographica in Canada. Copeia, 149:95. 
Pearse, A, S. 
1923. The Growth of the Painted Turtle. Biol. Bull., XLV:145. 
Ristey, P. L. 
1929. Anatomical Differences in the Sexes of the Musk Turtle, Sternotherus 
odoratus. Papers Mich. Acad. Sci., Arts, and Letters, X1:445-464. 
1933. Observations on the Natural History of the Common Musk Turtle, 
Sternotherus odoratus. Pap. Mich. Acad. Sci., Arts, and Letters, 
XVII:683-711. 
SHENCK, J. 
1886. Longevity of Turtles. Am. Nat., XX:897. 
SIEBENROCK, F. 
1907. Die Schildkrotenfamilie Cinosternidae. Sitz. Ber. Akad. Wiss. Wien 
(math.-nat.), 116, Abt. 1, pp. 527-599. 
1909. Synopsis der rezenten Schildkroten, mit Bericksichtigung der in histor- 
ischer Zeit ausgestorbenen Arten. Zool. Jahrb. Suppl., X:427-618. 
Storer, T. I. 
1932. The Western Limit of Range of Chrysemys picta bellii. Copeia, 1:9-11. 
Strecker, J. K. 
1915. Reptiles and Amphibians of Texas. Baylor Bull., X VIII:4:3-82. 
Strecker, J. K., and Hurter, J. 
1909. The Amphibians and Reptiles of Arkansas. Trans. Acad. Sci. St. Louis, 
XVIII:11-27. 
Stewart, N. H. 
1928. Some Rare Vertebrates of the Susquehanna Valley, Pennsylvania. Proc. 
Penn. Acad. Sci., 1:24. 
StroMstTeEN, F. A. 
1910. Nest Digging and Egg Laying Habits of Bell’s Turtle. Univ. Iowa 
Stud. Nat. Hist., X :67. 
Surrace, H. A. 
1908. Economic Features of Turtles of Pennsylvania. Zool. Bull. Div. Zool., 
Penn. Dept. Agr., VI:106-195. 
Viosca, P. 
1931. Amphibians and Reptiles of Louisiana. Southern Biological Supply Co., 
New Orleans. 
1933. The Pseudemys troostii-elegans Complex; A Case of Sexual Dimor- 
phism. Copeia, 1933:208-210. 


Witcox, L. 
1933. Incubation of Painted Turtle Eggs. Copeia, 1:41. 
YERKES, R. M. 
1904. Space Perception of Tortoises. Journ. Comp. Neur. and Physiol., 


XIV: 16-26. 
1905. The Color Pattern of Nanemys guttata. Science, N. S., 21:386. 
REFERENCES FOR STATES ADJACENT TO ILLINOIS 


The following few titles are intended to afford the student a starting point 
for references to the turtles of the adjacent states. 


THE TURTLES OF ILLINOIS—CAHN 213 


Wisconsin 
Cann, A. R. 
1929. The Herpetology of Waukesha County, Wisconsin. Copeia, 170:4-8. 
Hictey, W. K. 


1889. Reptilia and Batrachia of Wisconsin. Trans. Wis. Acad. Sci., Arts, and 
Letters, VII:155-176. 
Hoy, P. R. 
1883. Catalogue of the Cold-blooded Vertebrates of Wisconsin. Geol. of 
Wisconsin, I:422-426. 
Pore, T. E. B., and Dickinson, W. E. 
1928. The Amphibians and Reptiles of Wisconsin. Bull. Pub. Mus. City Mil- 
waukee, VIII:1-138. 


Indiana 
BLANCHARD, F. N. 
1925. A Collection of Amphibians and Reptiles from Southern Indiana and 
Adjacent Kentucky. Papers Mich. Acad. Sci. Arts, and Letters, 
V 3367-388. 
BLatTcH_ey, W. S. 
1891. Notes on the Batrachians and Reptiles of Vigo County, Indiana. Journ. 
Cine. Soc. N. H., XIV:22-35. 
EVERMANN, B. W., and Crark, H. W. 
1920. Lake Maxinkuckee. Indiana Dept. Conservation, Pub. 7, Vol. 1. 
Hay, O. P. 
1892. The Batrachians and Reptiles of the State of Indiana. An. Rept. Dept. 
Geol. Nat. Res. Indiana, 17:406-610. 
Myers, G. S. 2 
1925. A Synopsis for the Identification of the Amphibians and Reptiles of 
Indiana. Proc. Ind. Acad. Sci., XX XV:277-294. 
1926. Notes on Indiana Amphibians and Reptiles. Proc. Ind. Acad. Sci., 
XXXVI:337-340. 


Missouri 
Horter, J. 
1903. Second Contribution to the Herpetology of Missouri. Trans. Acad. Sci. 
St. Louis, XIII:77-86. 
1911. Herpetology of Missouri. Trans. Acad. Sci. St. Louis, XX:59-274. 


Iowa 
BLANCHARD, F. N. 


1922. The Amphibians and Reptiles of Dickinson County, Iowa. Univ. Iowa 
Stud. Nat. Hist., X:19-26. 
RutHven, A. G. 
1910. Contributions to the Herpetology of Iowa. Proc. Iowa Acad. Sci., 


19: 198-209. 
Ohio 
Morse, M. 
1904. Batrachians and Reptiles of Ohio. Proc. Ohio. St. Acad. Sci., IV: 
91-144. 
Smitu, W. H. 


1882. Report on the Reptiles and Amphibians of Ohio. Rept. Geol. Surv. 
Ohio., IV :633-734. 


214 ILLINOIS BIOLOGICAL MONOGRAPHS 


Michigan 


RutHven, A. G., THompson, C., and Gaice, H. T. 
1928. The Herpetology of Michigan. Univ. Mus., Univ. Mich., Mich. Hand- 
book Ser., No. 3. . 
SmirH, W. H. 
1879. Catalogue of the Reptiles and Amphibians of Michigan. Suppl. Sci. 
News, i-viil. 
Tennessee 
BLANCHARD, F. N. 
1922. The Amphibians and Reptiles of Western Tennessee. Occ. Pap. Mus. 
Zool., Univ. Mich., 117:1-18. 


Ruoapes, S. N. 
1895. Contributions to the Zoology of Tennessee, Proc. Acad. Nat. Sci. Phil., 
376-407. 


REFERENCES FOR SYNONYMY 


The following list includes works referred to in the synonymy of the genera 
and species, except those already given in the preceding sections of this bibliography. 
Baur, G. 

1893. Notes on the Classification and Taxonomy of the Testudinata. Proc. 

Am. Philos. Soc., 31:210-225. 
Bett, T. 
1826. A Monograph of the Tortoises having a Movable Sternum, with 
remarks on their arrangement and affinities. Zool. Journ., 2:299-310. 
Bonaparte, C. L. 
1830. Osservazione sulla seconda edizione del Regno Animale del Barone 
Cuvier. Bologna. 
BonnaTeErRE, [M. L’ApBe] 
1789. Tableau Encyclopédique et Méthodique des Trois Régnes de la Nature. 
Erpétologie. Paris. 
BriM.ey, C. S. 
1928. Two new Terrapins of the Genus Pseudemys from the Southern States. 
Journ. Elisha Mitchell Soc., 44:66-69. 
Corr, E. D. 
1872. Synopsis of the species of Chelydrinae. Proc. Acad. Nat. Sci. Phila., 
1872: 22-29. 
1895. Taylor on Box Tortoises. Am. Nat., 29:756-757. 
Cracin, F. W. 
1894. Herpetological Notes from Kansas and Texas. Colorado College Studies, 
5:37-39. 
Daupin, F. M. 
1802. Histoire Naturelle des Reptiles, 2:1-326. Paris. 
De Kay, J. E. 
1842. Zoology of New York, or the New York Fauna. Part III. Reptiles and 
Amphibia. Albany. 
Ditmars, R. L. 

1936. The Reptiles of North America. New York 
DumenriL, A, 

1851. Catalogue Méthodique de la Collection des Reptiles du Muséum d’His- 

toire Naturelle de Paris. Paris. 
DumeriL, A. M. C., and Breron, G. 
1834-35. Erpétologie Générale, 1(1834) :345-439; 2(1835):1-570. Paris. 


on 


THE TURTLES OF ILLINOIS—CAHN 21 


Ecker, E. C., and Paucmier, F. C. 
1902. Catalogue of New York Reptiles and Batrachians. Bull. N. Y. State 
Mus., 51:355-414. 
Firzincer, L. J. 
1835. Entwurf einer Systematischen Anordnung der Schildkroten nach den 
Grundsatzen der Natirlichen Methode. Ann. Wien, Mus., 1:103-128. 
FLEMMING, J. 
1822. Philosophy of Zoology. London. 


Fow er, H. W. 
1906. The Amphibians and Reptiles of New Jersey. Rep. N. J. State Mus., 
1906 : 23-376. 


GMELIN, J. F. 
1789. Systema Naturae, 1 :1036-1046. 


GRAVENHORST 
1829. Reptilia Musei Zoologica Vratislavensis Fasciculus Primus. Leipzig. 
Gray, J. E. : 
1831. Synopsis Reptilium, or Short Descriptions of the Species of Reptiles. 
London. 


1844. Catalogue of the Tortoises, Crocodiles, and Amphisbaenians in the 
Collection of the British Museum. London. 

1855. Catalogue of the Shield Reptiles in the British Museum. London. 

1869. Notes on the Families and Genera of Tortoises (Testudinata) and on 
the characters afforded by the study of their skulls. Proc. Zool. Soc. 
London, 1869: 165-225. 

1870. Supplement to the Catalogue of Shield Reptiles in the British Museum. 


London. 

1872. Appendix to the Catalogue of Shield Reptiles in the British Museum. 
London. 

1873. Hand-list of Specimens of Shield Reptiles in the British Museum. 
London. 


Hartan, R. 
1826. Genera of North American Reptiles and a Synopsis of the Species. 
Journ. Acad. Nat. Sci. Phila., 5:317-372 ; 6:7-37. 
1837. Description of a new species of Fresh Water Tortoise, Inhabiting the 
Columbia River. Am. Journ. Sci. Arts, 31:382-383. 
Hay, O. P. 
1903, Existing Genera of the Trionychidae. Proc. Am. Philos. Soc., 42:268-274. 
Heupe, M. 
1880. Memoire sur les Trionyx. Mem. Hist. Nat. Emp. Chinois, 1(pt. 1): 
v-vili + 1-38. 
Horsrook, J. E. 
1842. North American Herpetology, 1:1-152; 2:1-47. (2nd Ed.). Philadelphia. 
LaAcEPEDE, (COMPTE DE) 
1788. Histoire Naturelle des Quadrupédes Ovipares et des Serpents, 1:54-175. 
Paris. 
Le Conte, J. 
1830. Description of the species of North American Tortoises. Ann. Lyc. Nat. 
Hist. N. Y., 3:91-131. 
Le Sueur,.C. A. 
1817. An Account of an American Species of Tortoise, not noticed in the 
Systems. Journ. Acad. Sci. Phila., 1:86-88. 
1827. Note sur deux Espéces de Tortues du genre Trionyx Gffr. St. H. Mem. 
Mus. Hist. Nat. Paris, 15:257-268. 


216 ILLINOIS BIOLOGICAL MONOGRAPHS 


LINNAEUS, C. 
1758. Systema Naturae. Stockholm. 
LinpHoLm, W. A. 
1929. Revidiertes Verzeichnis der Gattungen der rezenten Schildkroten nebst 
Notizen zur Nomenklatur einiger Arten. Zool. Anz., 81:275-295. 
MAXIMILIAN, PRINCE zU WIED-NEUWIED 
1865. Verzeichnis der Reptilien, welche auf einer Reise im nordlichen Amerika 
beobachtet wurden. Nova Acta Acad. Leop. Carol., 32: viii + 141. 
Merrem, B. 
1820. Versuch eines Systems der Amphibien. Marburg. 
OKEN, L. 
1816. Lehrbuch der Zoologie. Jena. 
RAFINESQUE, C. S. 
1832. Atlantic Journal, 1:64. 


RITGEN. 
1828. Nova Acta Acad. Leop. Carol., 4:1:272. 
RutuHven, A. G. 


1924. A Check List of North American Amphibians and Reptiles. [Review.] 
Science, 59:339-340. 
Saves is 
1825. On the Fresh Water and Land Tortoises of the United States. Journ. 
Acad. Sci. Phila., 4:203-219. 
ScHNEIDER, J. G. 
1792. Beschreibung und Abbildung einer neuen Art von Wasserschildkrote. 
Schriften Ges. Naturf. Freunde Berlin, 10:259-283. 
Scuoeprr, J. D. 
1792. Historia Testudinum. Erlangen. 
Scuweiccer, A. F. 
1812. Prodromus Monographiae Cheloniorum. Konigsberg. 
1814. Prodromi Monographiae Cheloniorum. Ko6nigsberg. 
Sonnint, C. S., and Latremie, P. A. 
1802. Histoire Naturelle des Reptiles, 1:12-172. (Pagination of new edition.) 
Paris. 
STEJNEGER, L. 
1923. Rehabilitation of a Hitherto Overlooked Species of Musk Turtle of the 
Southern States. Proc. U. S. Nat. Mus., 62(Art. 6) :1-3. 
Stone, W. 
1903. A Collection of Reptiles and Batrachians from Arkansas, Indian Terri- 
tory, and Western Texas. Proc. Acad. Nat. Sci. Phila., 55:538-542. 
StraucH, A. 
1862. Chelonologische Studien. Mem. Acad. Sci. St. Petérsbourg, (7) 5:1-196. 
1865. Die Verteilung der Schildkroten tiber den Erdball, [bid., (7) 8:1-207. 
VAILLANT, L. 
1894. Essai sur la Classification générale des Cheloniens. Ann. Soc. Sci. Nat. 
Zool., (7) 16:331-345. 
Wac_LeR, J. 
1830. Naturliches System der Amphibien. Munich. 
Yarrow, H. C. 
1882. Check List of North American Reptilia and Batrachia, with Catalogue 
of Specimens in the United States National Museum. Bull. U. S. 
Nat. Mus., 24:1-249. 


THE TURTLES OF ILLINOIS—CAHN 217 


GLOSSARY 


Abdominal scutes: From the anterior end, the fourth pair of scales of the plastron. 

Alveolar surface: The flat masticatory surface of the jaws, lying just inside 
the cutting edge. 

Amphycoelous: A condition of the body (centrum) of the vertebra in which both 
ends are concave. 

Anal plates: The most posterior pair of scutes of the plastron. 

Anchylose: A fixed (fused) joint. 

Axillary plate: A small plate inserted in the anterior (axillary) margin of the 
bridge. 

Barbel: A short process of skin about the mouth, neck, or chin. 

Bridge: The lateral prolongation of the plastron, together with other elements, 
which meets the carapace. 

Callosity: A patch of hard skin on the plastron of soft-shelled turtles. 

Carapace: The upper (dorsal) portion of the shell of a turtle. 

Carinate: Keeled, or with a sharp ridge. 

Choana: The internal opening of the nostrils. 

Costal: Pertaining to the ribs; hence: the paired lateral scutes of the carapace. 

_ Costiform: Rib-like. 

Cruciform: Shaped like a cross. 

Dermal skeleton: The bony skeleton of the shell. 

Emarginate: With a broad, shallow notch. 

Entoplastron: The only unpaired bony element of the dermal skeleton of the 
plastron. 

Epidermal skeleton: The scale-like shields or scutes which cover the dermal 
skeleton of most turtles. 

Epiplastra: The most anterior, paired bony elements of the dermal skeleton. 

Femoral scutes: From the anterior end, the fifth pair of scales of the plastron. 

Gulars: The most anterior pair of scutes of the plastron. 

Hinge: A ligamentous, flexible joint in the plastron. 

Humerals: The second most anterior pair of scutes of the plastron. 

Hyoplastra: From the anterior end, the second pair of bony elements of the 
dermal skeleton. 

Hypoplastra: The third most anterior pair of bony elements of the dermal 
skeleton. 

Inframarginals: Secondary scutes lying below (ventral) the marginals. 

Inguinal: A small plate inserted in the posterior (inguinal) margin of the bridge. 

Intergular: An unpaired element located anterior to the gular scutes in a few 
turtles. 

Keel: A well-defined ridge. 

Lobe: The region of the plastron anterior or posterior to the bridge. 

Marginals: Scutes forming the lateral margin of the carapace. 

Neurals: The middle (unpaired) series of bony elements of the dermal skeleton of 
the carapace. 

Notch: A sharp V-shaped indentation. 

Nuchal: The most anterior, unpaired, median marginal scute. 

Opisthocoelous: The condition in the body (centrum) of the vertebra in which the 
anterior face is convex, the posterior face concave. 

Papilla: A small fold of the mucous membrane within the nose. 

Pectoral scutes: From the anterior end, the third, paired, set of scutes of the 
plastron. 


218 ILLINOIS BIOLOGICAL MONOGRAPHS 


Plate: A scute; usually designating a heavy scale. 

Plastron: The ventral portion of the shell of a turtle. 

Procoelous: The condition in the body (centrum) of a vertebra in which the 
anterior face is concave, the posterior convex. 

Pygals: The scutes above the tail; supracaudals; caudal marginals. 

Reniform: Kidney-shaped. 

Reticulate: Net-like. 

Rugae: Small folds; wrinkles. 

Scute: A scale; one of the component elements of the epidermal skeleton. 

Serrate: Toothed; saw-edge. 

Shield: A scute. 

Submarginal: Below the marginal scutes. 

Supracaudal: Above the tail; the most posterior pair of marginal scutes; caudal 
marginals; pygals. 

Supramarginals: Accessory marginal scutes located above the marginals. 

Symphysis: The fixed union along the midline between paired bones. 

Temporal arch: A bony bar extending from the quadrate to the upper jaw. 

Truncate: Having a square or even edge. 

Tubercle: A short, knob-like protuberance. 

Vertebral: The median, unpaired scutes of the carapace. 

Wing: The lateral prolongation of the elements of the plastron which aid in 
forming the bridge. 

Xiphiplastra: The most posterior paired bony elements of the dermal skeleton of 
the plastron. 


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