274 CROCODILIDJi). 



Fam. 1. CROCODILID^. 



Crocodllidfc, Gray, Ann. Phil. (2) x. 182o. 



Crocodiliens ou Aspidiotcs, Dumeril ^ Bibron, Erp, Gen. iii. 1830. 

 Crocodilidoe, AUigatoridse, Gray, Cat. Turt. kc. 1844. 

 Gavialidoe, Crocodilidpe, Alligatorida?, Iluxhy, Journ. Linn. Soc. iv. 

 1860 ; Gray, Cat. Sh. lieid. ii. 1872. 



Narcs anterior ; choauffi opening far back between the pterygoids, 

 which, like the palatines and maxillaries, arc produced into osseous 

 plates joining on the median line of the palate ; orbit communi- 

 cating with the infratemporal fossa. Vertebrte 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 PerosucJms fuscus, the three inner digits are clawed. 



Syno2)sis of the Genera. 



I. Nasal bones widely separated from the nasal apeiture ; splenial 

 elements entering the mandibular symphysis, which extends at 

 least to the fifteenth tooth. 



P^ teeth on each side, none of the mandibular received into pits ; 

 nasal bones widely separated from the pra^maxiUaries. 



1. Gavialis, p. 275. 



20-21 

 18-19 



teeth on each side, the lateral mandibular received into pits 

 between the maxillary teeth ; nasal bones in contact with the 

 l)ra3maxillaries 2. Tomistoma, p. 270. 



IT. 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 ; |^g teeth on each side. 



No bony nasal septum 3. Crocodilus, p. 277. 



Nasal bones dividing the nasal aperture . . 4. Osteolaemns, p. 288. 



B. Fourth mandibular tooth usually fitting into a pit in the 



upper jaw ; J|^ teeth on each side. 



Nasal bones dividing the nasal aperture; dorsal bony scutes not 

 ariiculated 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 . 



