274 CROCODILIDZ. 
Fam. 1. CROCODILIDZ. 
Crocodilidee, Gray, Ann. Phil. (2) x. 1825. 
Crocodiliens ou Aspidiotes, Duméril § Bibron, Erp. Gén. iii. 1836. 
Crocodilide, Alligatoridee, Gray, Cat. Tort. &c. 1844. 
Gavialidee, Crocodilide, Alligatoridee, Huvley, Journ. Linn. Soc. iv. 
1860; Gray, Cat. Sh. Rept. ii. 1872. 
Nares anterior ; choanse opening far back between the pterygoids, 
which, like the palatines and maxillaries, are produced into osseous 
plates joining on the median line of the palate ; orbit communi- 
cating with the infratemporal fossa. Vertebre proccelous; ribs 
with uncinate processes. No clavicles. Pubis excluded from aceta- 
bulum. Manus with five well-developed digits, pes with four. A 
dorsal armour of bony scutes. Ears with movable opercles. 
The pupil is vertical in all the species. With the possible ex- 
ception of Perosuchus fuscus, the three inner digits are clawed. 
Synopsis of the Genera. 
I. Nasal bones widely separated from the nasal aperture ; splenial 
elements entering the mandibular symphysis, which extends at 
least to the fifteenth tooth. 
a teeth on each side, none of the mandibular received into pits ; 
nasal bones widely separated from the preemaxillaries. 
1. Gavialis, p. 275. 
= teeth on each side, the lateral mandibular received into pits 
between the maxillary teeth; nasal bones in contact with the 
PLCCMARTMATICS § yay ofc ereie cos oersvegers 2. Tomistoma, p. 276, 
II. Nasals entering the nasal aperture; splenial elements not 
entering the mandibular symphysis, which does not extend 
beyond the eighth tooth. 
A, Fourth mandibular tooth usually fitting into a notch in the 
upper jaw ; jy; teeth on each side. 
Nojbony nasaliseptum® 24-4 2315<.20 se cure 3. Crocodilus, p. 277. 
‘Nasal bones dividing the nasal aperture .. 4. Osteolemus, p. 288. 
B. Fourth mandibular tooth usually fitting into a pit in the 
upper Jaw ; = =. teeth on each side. 
Nasal bones dividing the nasal aperture; dorsal bony scutes not 
articulated together ; ventral bony scutes absent or very thin. 
5. Alligator, p. 289. 
No bony nasal septum; a dorsal and a ventral armour of articulated, 
overlapping bony scutes ............ 6. Caiman, p. 291. 
