204 RITTILIA : TKSTUDINATA. — XXX. 



pioro. The osseous plates, both alx)ve ami below, eorrespond neither 

 in nmnber nor positiciii with the overlying (iernial jilates. 



The skull is more lonipaet than that of the other n-ptiles. There 

 are no teeth, but the jaws are enca.seii in li(jrny sheaths, usually 

 with .»iiiarp cuttin'r ed^jjes ; the eye is furnished with two lids and a 

 nictitating membrane as in the birds; the tympanic membrane is 

 always ])resent, although sometimes hidden by the skin. Respira- 

 tion is effected by swallowing air. (Lat., le.sludo, tortoise.) 



Families of Testudinata. 



a. Limbs developed as paddles, not capable of distinct movements at wrist or 

 nnkli'-joiiit; dijcits flattened, elongated, bound inunovably together by the 

 iiitfguMK'iit. (Sea Turtles.) 

 b. Feet scaleless, the anterior very large. . . Dhg[{MOCHEi.YDin.«, 117. 



bb. Feet scaly; carai)ace heart-shaped Cheu).niid.k, 118. 



aa. Limbs not in the form of paddU-s, capable of movement at wrist and 

 ankk'-joints. (I>and and pond-turtles.) 



c. Carapace leathery, its margins flexible; no dermal plates; toes 5-5, 

 the claws '6-3; head small, the snout pointed; body very fiat. 



Tkio.nvchid.k, 119. 

 cc. 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-sliupcd, with 9 plates (besides the bridge); 

 head large; body highest in front. . . . Chelyukiu.k, 120. 

 ee. Tail short, not crested; plastron broad. 

 y. Lower jaw ending in a long sharp point ; carapace highest be- 

 hind the middle, its edge not flaring outward; ida^tron with 9 



or 11 plates Ki.NosTKn.Nin.*^ 121. 



jy. Lower jaw without long point at symphysis; carapace highest 

 at al)out the middle, its edge flaring outward; plastron with 12 



dermal plates EMvnin.K, 122. 



dd. Fingers and toes hound closely together, only the last joint free; 

 plastron very broad Testlpi.niu.k, 123. 



Family CXVII. DERMOCHELYDID.^. (Thk Leatheu- 



Tukti.es.) 



Sea turtles with the body covered by a smooth leathery skin ; 

 carapace with several louiritudinal ridges with deep grooves Ix'tween 

 them; iMxly highest in front anil widest just Infore l)rid'je ; hind legs 

 much exposed ; toes without nails ; hciwl short, high, v»Ty broa<l 

 In-hind ; uppi-r jaw with 2 pits and 2 tooth-like projections. One 

 sjH'cies, widely distributed. 

 301. DERMOCHELYS iJlainville. (bi^)^J.a, skin; x«Xef. tortoise.) 



595. D. coriacea (Vamhlli). Tkink-hack. LEATiiKU-Tru- 

 Ti.E. Diirk l.rnwn. L. 6 to 8 feet. ()j)en sea, N. to Cape iSun. 

 (Lai., l.alh. ry.) (A'".) 



