18. ISCnNOGNATHTJS. 285 



Rostral as deep as broad ; iiiternasals snbcrescentic, forming 

 together a triangle ; two pra'frontals ; frontal as broad as long ; 

 one pra3- and one postocular, and three suboculars separating the 

 eye from the labials ; twelve upper labials, third to tenth separated 

 from the edge of the mouth by a row of small trigonal scales. Scales 

 in 17 rows, striated and strongly keeled. Yentrals 170 ; anal divided; 

 subcaudals 95. Olive above, the scales with a whitish edge ; lower 

 parts and outer row of scales yellow. 



Kaju Tanam, Sumatra. 



4. Opisthotropis typica. 



Helicopsoides tvi)icus, Mncquard, Lo. Kiitiir. 1890, p. 154, and Nouv. 



Arch. Mns. (3) ii. 1890, p. 141, pi. ix. lig. 3. 

 Opisthotropis typica, Bouleng. Ann. t^- Mag. N. II. (6) vii. 1891, 



p. 343. 



Snout short and broad, much depressed. Rostral twice as broad 

 as deep : nasals semidivided, in contact behind the rostral ; inter- 

 nasals small, triangular ; a pair of pra^frontals ; frontal large, 

 pentagonal, as long as broad ; supraociilar very small ; loreal 

 elongate, partly or completely divided ; two prae- and two post- 

 oculars ; three suboculars separating the eye from the labials ; 

 temporals 1 + 1 + 2 ; eleven upper labials, seventh and eighth 

 below the eye, the six anterior twice as deep as long, the four last 

 divided as in the preceding species. Scales in 19 rows, striated 

 and keeled. Ventrals 176 ; anal divided ; subcaudals 82. Uniform 

 olive-brown above, dirty yellow below. 



Total length 390 millira. ; tail 95. 



Mt. Xiua Raloo, jS'orth Borneo. 



18. ISCHNOGNATHUS. 



Ischnognathus, Dum. t^- Bibr. Mini. Ac. So. xxiii. 1853, p. 468, and 

 Erp. Gen. vii. p. 506 (1854) ; Gmdh. Cat. Col. Sn. p. 80 (1858) ; 

 Ja7i, Arch. Zool. A7iaf. Phys. iii. 1865, p. 238. 



Storeria, Baird 6,- Gir. Cat. N. Am. liept. p. 135 (1853). 



Microps {lion Megeiie), Hallow. Froc. Ac. Philad. 1856, p. 240. 



Tropidoclonion, Cope, Proc. Ac. Philad. 1860, p. 76, a7id Proc. U.S. 

 Aat. Mns. xiv. 1892, p. 666. 



Cora, Jan, I. c. 



Adelophis {Duges), Cope, Proc. Am. Philos. Soc. xviii. 1879, p. 265. 



Clonophis, Cope, Proc. U.S. JVat. Mus. xi. 1889, p. 391. 



Maxillary teeth 14 to 18, equal; mandibular teeth equal. Head 

 slightly distinct from neck : eye rather small, with round pupil ; 

 loreal shield present or absent. Body moderately elongate, cylin- 

 drical ; scales keeled, with or without apical pits, in 15 to 19 rows ; 

 ventrals rounded. Tail moderate ; subcaudals in two rows. Hypa- 

 pophyses developed throughout the vertebral column. 



North and Central America. 



