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



eeras a genus which comprised three subgenera, Stephanoceras, 

 Perisphinctes, and Cosmoceras ; subsequently he raised each of 

 these subgenera to the rank of distinct genera. Examples : 

 S. Humph riesianum, macroceplialum, coronatum, Parhmsoni. 



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

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

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

 tinsi, plicatilis, hiplex, Calisto. 



Peltocbras, "Waagen, 1871, 91. Includes the species detached from 

 the genera Perisphinctes and Aspidoceras. Jurassic. Examples: 

 P. arduennense, transversarium, athleta. 



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

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

 C calloviense, ornatum, mamillare, verrucosum. 



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

 biruncinatum, strictum, catrianum. 



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

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

 amples : A. hifplnosum, cydotum, ortJioceras, Lallierianum, iphi- 

 cerus, rogozniceiise. 



XLIII. — Description of a new Snahe from Madagascar. 

 By Dr. A. Gunther. 



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 Dendro^liidoe. 



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 prge-, three postoculars. 

 Pupil round. None of the anterior or middle maxillary teeth 

 enlarged ; posterior maxillary tooth grooved. 



Ithycyphus caudolineatus. 



Body slender, compressed ; head narrow, flat, with the 

 snout depressed, obliquely truncated in front. Eye rather 

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

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



