204 REPTILIA : TESTUDINATA. — XXX. 
piece. The osseous plates, both above and below, correspond neither 
in number nor position with the overlying dermal plates. 
The skull is more compact than that of the other reptiles. There 
are no teeth, but the jaws are encased in horny sheaths, usually 
with sharp cutting edges; the eye is furnished with two lids and a 
nictitating membrane as in the birds; the tympanic membrane is 
always present, although sometimes hidden by the skin. Respira- 
tion is effected by swallowing air. (Lat., testudo, tortoise.) 
Families of Testudinata. 
a. Limbs developed as paddles, not capable of distinct movements at wrist or 
ankle-joint; digits flattened, elongated, bound immovably together by the 
integument. (Sea Turtles.) 
b. Feet scaleless, the anterior very large. . . DERMOCHELYDID4, 117. 
bb. Feet scaly; carapace heart-shaped. . . . . . CHELONIIDA, 118. 
aa. Limbs not in the form of paddles, capable of movement at wrist and 
ankle-joints. (Land and pond-turtles.) 
c. Carapace leathery, its margins flexible; no dermal plates; toes 5-5, 
the claws 38-3; head small, the snout pointed; body very flat. 
TRIONYCHID&, 119. 
ec. Carapace firm, ossified; dermal plates present; claws mostly 5-4. 
d. Fingers and toes spreading, not closely bound together, more than 
one joint being free. 
e. Tail very long and strong, with a crest of tubercles; plastron nar- 
row and small, cross-shaped, with 9 plates (besides the bridge) ; 
head large; body highest in front. . . . CHELYDRID#, 120. 
ee. Tail short, not crested; plastron broad. 
Jj. Lower jaw ending in a long sharp point; carapace highest be- 
hind the middle, its edge not flaring outward; plastron with 9 
or.11 plates: 224 2 . » » » KINOSTERNID&, 121. 
Jf. Lower jaw without long othe at symphysis; carapace highest 
at about the middle, its edge flaring outward; plastron with 12 
dermal plates. «2» «© «,*, 2 ¢ « » . EM¥DIDay 122, 
dd. Fingers and toes bound closely together, only the last joint free; 
plastron very broad. . . 6 » « + « « TESTUDINIDA, 123. 
Famity CXVII. DERMOCHELYDIDA, (Tue LEATHER- 
TURTLES.) 
Sea turtles with the body covered by a smooth leathery skin ; 
carapace with several longitudinal ridges with deep grooves between 
them; body highest in front and widest just before bridge ; hind legs 
ake exposed ; toes without nails; head short, hich, very broad 
behind; upper jaw with 2 pits and 2 tooth-like projections. One 
species, widely distributed. 
301. DERMOCHELYS Blainville. (8épya, skin; yédvs, tortoise.) 
595. D. coriacea (Vandelli). Trunx-pack. LEATHER-TUR- 
TLE. Dark brown. L. 6 to 8 feet. Open sea, N. to Cape Ann. 
(Lat., leathery.) (Eu.) 
