NATURAL SCIENCES OP PHILADELPHIA. 563 



"occipital and a large temporal plate. As second large temporal, separating 

 the last upper labial from the occipital. Superior labials nine, fourth, fifth 

 and sixth entering the orbit ; seventh subtrigonal, last two elongate. Inferior 

 labials ten; post-genials longer than anterior. Gastrosteges not angulated, 

 153 in number. 



Coloration. A light brownish fulvous, paler on the belly, darker upon the 

 occipital region. 



One specimen, native country unknown, but may perhaps prove to be from 

 Eastern Asia or Malaysia. 



Zaocys nobis. Type Z. dhumnades. 



Form slender, vertebral line angular. Two medial series of dorsal scales ; 

 those of the sides quincuncially arranged. Two nasals, one loreal, two pre- 

 ocular shields. 



The large isodont serpents which have the median dorsal line elevated into 

 a ridge, and the sides compressed more or less "era toit" appear to us to be 

 naturally distinguished as follows : 



A. Two median dorsal series of scales. 



Herpetodryas. Scales in more or less transverse series, one preocular. 

 Zaocys. Scales in quincunx ; two preoculars. 



B. One median dorsal series of scales. 



a. Loreals more than one. 

 Ptyas. Preoculars two or more. 



b. Not more than one loreal or preocular. 



Spilotes. Scales in sub-transverse series; head very distinct from neck ; 



loreal trapezoidal. 

 Coelognathus. Scales quincuncial ; head but little distinct; loreal trape- 

 zoidal. 

 Gonyosoma. Loreal three times as long as high or absent; muzzle very acute. 

 In proposing the name Zaocys for the Coryphodontes carinatus and 

 fuse u s of Gunther. and in retaining Fitzinger's name Ptyas for the C. B lu- 

 menbachii and C. korros of the Erpetologie General, we are giving ex- 

 pression to an opinion long held by us, as to the unnatural association of 

 species in the so-called genus Coryphodon, of those authors. In it we find 

 cylindrical terrestrial serpents united with compressed subarboricole species, 

 upon a peculiarity whose value as an index of nature appears to us entirely 

 imaginary. The very nature of the coryphodontian type of dentition as dis- 

 tinguished from the isodontian and syncranlerian would lead us to infer its in- 

 constancy ; and it does exist, we believe, in species claimed to be isodont ; e. g. 

 in the genera Lampropeltis, Drymobius, etc. 



205. Z. dhumnades nobis. Coluber dhumnades Cantor, 1842. " C. nigromargi- 

 natus Blyth. 1855." Coryphodon carinatus Gthr., 1858. 



Three sp. Ningpo. China. Dr. McCartee. 



Besides the species of this genus, and of Herpetodryas, Dendrophis pseu- 

 dodipsasof Bianconi, from Mosambique, possesses two medial dorsal series 

 of scales. 



Ptyas Fitz. Type P.macosus, 



Systema Reptilium, p. 26, 1843. 



206. P. m u c o s us nobis. Coluber mucosas Linn. Col. BlumenbachiiMeT Te w. 

 Coryphodon Blumenbachii Dum. & Bibr. Ptyas Blumtnbachii Fitz. 



One sp. East Indies, Mr. Yarrow 



207. P. korros nobis. Coluber korros Reinwt., Schleg. Coryphodon korros 

 Dum. & Bibr. Coluber cancellatus Oppel. 



One sp. (80 in.) Siam, Dr, Ruschenberger. 



One sp. ? ? 



I860.] 



