OF RECENT CROCODILIAJS'S. 



153 



The skull of the Alligator palpehrosus is easily known from that of this species even 

 in the young by the cheeks of the former being flattened and nearly erect, and of the 

 latter spread out, and in the supratemporal fossse being open, while in the Alligator they 

 are closed even in the young specimens. 



Most probably it was from the examination of a skull of this Crocodile that the 

 statement has arisen that in some Alligators the canine teeth sometimes fit into a notch 

 in the upper jaw, and not into a pit as they normally do in that genus. 1 will not under- 

 take to say that such an abnormal state does not exist in the genus Alligator ; but 

 I have not observed it. 



Halceosia nigra (Black African Crocodile). (Plate XXXI. figs. 4, 5, G.) 

 Krokodile noir du Niger, Adanson, MS., Miis. Paris. See Cuvier, Oss. Poss. iii. 41. 

 Crocodilus niger, Latr. H. N. Rept. i. .510, from Adanson. 

 Crocodilus palpebrosus, var. 2, Cuvier, Oss. Foss. iii. 41, t. 2. f. 6 (part.). 

 Crocodilus trigonatus (part.), Cuvier, Oss. Foss. iii. 65. 

 African Black Crocodile, Gray, Rep. Brit. Assoc. 1862, Sections, 107. 

 Osteolmnus tetraspes. Cope, Proc. Acad. N. S. Philad. xii. 550. 

 Crocodilus frontatus,A.yLuy:ra.j, Proc. Zool. Sec. 1862, pp. 139, 213,fig. liead, t. 29. by Ford. Straucli, 



Syn. Croc. t. 1 (head, young) . 

 Halcrosia frontata, Gray, Ann. & Mag. Nat. Hist. 3rd series, x. 277. 



Eab. West Africa : Senegal {Adanson) ; Gaboon ; Old Calabar ; Ogobai River {Cope). 



Fis;. 11. ..nmi— ^'S- ^^^ 



Fig. 12. 



Wa 14 





Fi-'S. 11-14. Head and cervical and nuclial plates of young Hahrosin iwp-n 



