CHELONIIDA. — CXVIIL. 205 
~Famity CXVUI. CHELONITIDA. (Loccer-weap 
TURTLES.) 
Sea turtles, with the carapace covered with bony plates; carapace 
heart-shaped, broad and flat, highest in front, widest near middle ; 
head large, jaws without tooth-like projections. Genera 4; species 
about 7, of the open sea, coming to shore only to deposit and bury 
their eges. 
a. Scales around large median plate on top of head 13 to 20; plates of carapace 
not imbricate; edge of lower jaw not serrate; costal plates 5 on each side; 
scales on cheeks small, 15 to 20; head broad. . THALASSOCHELYs, 3802. 
aa. Scales around vertical plate 7; costal plates 4. 
6. Tomia of lower jaw not serrate; shields of carapace imbricated; scales on 
cheeks large, 7 to 10; head broad.. . . . . ERETMOCHELYs, 303. 
bb. Tomia of lower jaw serrate; shields of carapace not imbricated; scales 
on cheeks small, 15 to 20; head high and narrow. . CHELONTIA, 304. 
302. THALASSOCHELYS Fitzinger. (@dd\agca, sea; 
xeAus, tortoise. ) 
596. T. caretta (L.). LOoGGER-HEAD TurRTLE. Scales not 
imbricate ; 2 nails to each foot. Atlantic, N. to Mass.; reaches 
450 lbs. (#u.) (An old name.) 
303. ERETMOCHELYS Fitzinger. (é€perpds, oar; yédus.) 
597. E. imbricata (L.). TorrToise-sHELL TurTLE. Hawks- 
BILL TuRTLE. Jaws produced in a beak; nails two. N.C. to 
Brazil. Smaller and fiercer than the preceding, its scales used in 
making combs. 
304. CHELONIA Brongniart. (yeAovn, tortoise.) 
598. C. mydas (L.). GREEN TuRTLE. Plates thin; nail sin- 
gle; body oblong. LL. I. to Brazil, herbivorous, reaching 850 lbs., 
and valued as food. (j:vdaa, to be wet.) 
Famity CX1IX. TRIONYCHIDAL. (Tue Sort-sHELLED 
TURTLEs.) 
Body flat, nearly orbicular ; carapace not completely ossified, the 
ribs projecting freely towards the outer extremities ; marginal ossi- 
cles rudimentary ; carapace and plastron covered by a thick leathery 
skin which is flexible at the margins. Head long and pointed, with 
a long, flexible, tubular, pig-like snout; neck long. Feet broadly 
webbed ; toes long, 5-5, but the claws only 3-3. 
Aquatic, carnivorous and voracious; species about 30, in both 
hemispheres. 
a. Nostrils rather under the tip of snout; nasal septum without an internal 
longitudinal ridge on each side; head narrow; edge of upper jaw serrate 
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