374 Dr. A. Giinther on a new Snake from Madagascar. 



ceras a genus which comprised three subgenera, Stephanoceras, 

 PerispJiinctes, and Cosmoceras ; subsequently he raised each of 

 these subgenera to the rank of distinct genera. Examples : 

 S. Humphriesianum, macrocephalum, coronatum, Parlinsoni. 



Perisphinctes, Waagen, 1869, 248. Zittel, 1870, 218. _ Waagen, 

 1870, 206. Planulati, Yon Buch ; partim macrocephali, coronati, 

 coronarii, dentati. Jurassic and Cretaceous. Examples ; P. Mar- 

 tinsi, plicatilis, biplex, Calisto. 



Peltoceras, Waagen, 1871, 91. Includes the species detached from 

 the genera Perisphinctes and Aspidoceras. Jurassic. Examples:' 

 P. arduennense, transversarixtm, athleta. 



Cosmoceras, Waagen, 1869, 248. Zittel, 1870, 215. Waagen, 

 1870,208. Dentati, omati. Jurassic and Cretaceous. Examples: 

 G. calloviense, ornatum, mamillare, verrucosum. 



SiMocERAS, Zittel, 1870, 207. Tithonic. Examples : S. volanense, 

 hiruncinatum, stnctum, catrianum. 



AspiDocERAS, Zittel, 1868, 116. Waagen, 1869, 248. Zittel, 1870, 

 192. Middle and Upper Jurassic and Lower Cretaceous. Ex- 

 amples : A. bispinosum, cyclotum, orthoceras, LaUierianum, iphi- 

 cerus, roijoznicense. 



XLIII. — Description of a new Snake from Madagascar. 

 By Dr. A. Gunthek. 



The Trustees of the British Museum have purchased some 

 specimens of reptiles from Madagascar, and among them a 

 snake which appears to be the type of a new genus of the 

 family Dendrojjfhidce. 



Ithycyphus. 



Body compressed, with the abdominal scutes distinctly 

 keeled. Scales smooth, imbricate, without apical groove, in 

 twenty-one series. Ventral scutes less than 200 ; anal and 

 subcaudals divided. Upper shields of the head normal. One 

 undivided nasal ; loreal distinct ; one pr«-, three postoculars. 

 Pupil round. None of the anterior or middle maxillary teeth 

 enlarged ; posterior maxillary tooth grooved. 



Ithycyphus caudolineatus. 



Body slender, compressed ; head nan'ow, flat, with the 



snout depressed, obliquely truncated in front. Eye rathei^ 



small. Vertical bell-shaped. Nostril round, in the middle oi 



the narrow, elongate, single nasal shield. Loreal elongate, as 



