NATURAL SCIENCES OF PHILADELPHIA. 339 



Tharnnophis, viz.: Prymnomiodon. Bascanium anthicum is very nearly 

 allied to B. constrictor: the only differences are in the outline of the 

 front plane iu the former, arched in the latter the more convergent canthus 

 rostrales of the latter, and that of coloration. 



Urieehis nigriceps Peters, Homalosoma lutrix, Philothamnus semi- 

 variegatus, Bucephalus typus vars. B. C. D., Causus rhombeatus 

 and Ciotho a r i e t a n s have been sent to the Academy from Umvoti, Natal, 

 by our correspondent, the Rev. Dr. Grout. 



Contia m o d e s t a. 



Ablabes modest us Gunther. 

 From Ooroomiah. This species belongs to the same genus as the American C. 

 e p i s c o p a and C. m i t i s, which principally differs from the Homalosoma* of 

 Africa in a divided anal plate. Perhaps the " Ablabes" with two nasal plates be- 

 long to a different genus : at all events the name adopted by most herpetologists 

 must give way to Fitzinger's Lycodonomorphus, proposed for the Coronella 

 ru f u 1 a long previously, f Fitzinger did not give characters to his genera, on 

 which account they ought to be rejected, were it not that it is impossible for 

 naturalists to arrive at an agreement as to what constitutes a good, sufficient, 

 insufficient, or mil diagnosis. It seems also to be rightly conceded by many, 

 that an author cannot change his own name, if it be not preoccupied or false 

 in signification. Thus, Wagler's Catostoma should be retained, though he 

 afterwards altered it to Geophis (which I overlooked on a former occasion), 

 as it is sufficiently distinct from Catostomus. 



Rhoptrura Peters has been suspected by met to be identical with Charina 

 Gray, on account of the entrance of the style of structure of the plates as 

 described by Dr. Gray, within the extensive range of variation exhibited by 

 the latter genus. Prof. Peters has, however, shown that it does not possess 

 palatine teeth ; this character at once separates it from all other Peropoda. 



Cryptoblepharus w a h 1 b e r g i i Smith. 



From Umvoti, Southeastern Africa, whence also has been received Euprepis 

 vittatus Gray, and a variety which is light olivaceous above ; on each 

 side a light band, which is dark-bordered above. Other markings obsolete. 



Gerrhosaurus b i b r o n i i Smith. 



Brown bordered. The internasal plate is very transverse, as figured by 

 Wagler in the flavigularis, and widely removed from contact with the 

 frontal by the extensive intervention of the contiguous fronto-nasals. Dr. 

 Smith figures the latter as separate, and the former in contact, in both species. 



Mancus macrolepis Cope. 



Char. gen. The same as that of Chamaesaura, except in the absence of 

 the anterior pair of extremities. Tongue slightly emarginate at the tip. 

 The animal upon which this genus is established, so closely resembles 

 in generic and specific peculiarities the Chamaesaura anguina, that it 

 may be doubted whether it is entitled to the distinction I have proposed 

 for it. The question of the disappearance of organs is one of much interest. 

 Our impression of the importance of a peculiarity as affecting generic 

 or specific rank is derived from consideration of its constancy during 

 the adult age of the animal. That the assumption of generic structural 



* Another genus, which only differs from Homalosoma in its more slender tail and 

 diacranterian dentition, is Cryptodacus, (Gundlack, Monatsb. Akad. Berlin, 1861, 1002.) 

 C. vittatus is found in Cuba; it was described in November. In the following Feb- 

 ruary the author introduced it as Arrhyton bivittatum (in Proceed. Philada. Acad.) The 

 specimen described wants the dorsal band. 



t Proceed. Acad. Nnt. Sci. Philada., 1860, p. 256. 



t L c, p. 305. 



1862.] 



