NATURAL SCIENCES OF PHILADELPHIA. 185 



Third contribution to the HERPETOLOGY of Tropical America. 



BY E. D. COPE. 



Alligator h el o i s. 



Muzzle 6| inches from end to lines connecting orbits, 5| inches wide near 

 the middle. Two keels behind and between the eyes, diverging posteriorly, 

 a short and nearly transverse keel in front of the eyes. Upper eye-lid divided 

 by grooves into three areas ; an elevated keel, above each ear opening. Two 

 oblique rows of elevated horn-like shields^n each side of the neck, of rather 

 small size, four on the inner, three on the outer rows ; the third of the inner 

 and second of the outer form, with two large elevated median plates, a trans- 

 verse row. Four very high, short, keel-like postcervicals. Eight rows of 

 dorsal shields, excepting anteriorly where there are six in the first cross-row. 

 and four in the two succeeding ; all are like heads of spikes keeled. Four 

 rows on the tail at its middle. Lateral caudal shields continuous, abrttptly 

 elevated. like the dorsals, subquadrate. Sides with small rounded scales ; 

 width between dorsals and ventrals equal to length of third dorsal cross series. 

 A large row of plates on the inner side of the fore arm. Claws long ; no pal- 

 mar webs. Abdominal rows eleven, each plate with a thin ossification ; two 

 or three large plates in the thoracic cross-row. End of tail little serrate above, 

 scarcely compressed. From end of muzzle to occipital 12 inches ; to between 

 femora 32 inches ; from latter point to end of tail 50 inches ; total 7 feet 10 

 inches. 



Color dark brown with vertical yellow bars on the sides and tail, the former 

 very irregular. Chin, throat, under and upper lips yellow, without spots. 



This rugged looking species belongs to the genus Alligator, as restricted by 

 Gray, in which the prolongation of the nasal bones separates the external 

 nares, and there is no cross ridge between the orbits. It approaches Jacare 

 in that an external portion of this cross-ridge exists on each side. The hab- 

 itat is not known, as the single specimen I have seen is preserved without 

 label in the Museum of the University of Munich. Through the courtesy of 

 Prof. C. Von Siebold, I was enabled to make the above description. 



I may mention here that the crocodile described by me (Proc. Acad. 1860, 

 550) as Mecistops bathyrhynchus, is the species identified by Dr. Gray 

 (Catal. Brit. Mus.) with the C. intermedins Graves; with the limited pub- 

 lished material as a basis, I have reached a different conclusion. 



Chelopus punctularius, Emys punctularia Daud., E. scabra Bell, Gray, 



Linnaeus (fide Agass. 



At first sight, the female of this animal gives the impression of a Testudinid 

 form, with separate caudal plates, but an examination of the phalanges shows 

 their number to be that in the Emydidae, two for the longest digits, (exclusive of 

 ungueal,) instead of but one remaining upon the extinction of the proximal, 

 as in the former. The proximal phalanx is articulated somewhat, as in Cistudo, 

 but is shorter, and nearly excluded from a serial connection ; its proximal 

 glenoid cavity is superior, and near the distal condyle. The inferior projec- 

 tion of the proximal end gives the foot its angulated outline. The structure 

 is not unlike that in Chelopus muhlenbergii, and there are really more pha- 

 langes than in Cistudo, where the foot is longer ; the external digit behind 

 having two internal phalanges instead of but one. In similar manner the re- 

 duction of the penultimate phalanx in the parallel Sternothaerus, prepares us 

 for its absence in Pelomedusa*, the extreme of the Pleurodera in this direc- 

 tion, and representative of the Testudinidae. Podocnemys and Peltocephalus 

 imitate the Cheloniidae in their overarched temporal fossae, as observed by 

 Wagler, while intermediate forms are more or less similar to some Emydidae. 

 After a consideration of various osteological peculiarities, I incline to differ 



Which has not, I believe, been previously noticed. 



1865.] 



