18. ISCHKOONAIHTJS. 28& 



Eostral as deep as broad; internasals siibcrescentic, forming 

 together a triangle; two prsefrontals ; frontal as broad as long; 

 one prse- 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. Ventrals 170 ; anal divided j 

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

 parts and outer row of scales yellow. 



Kaju Tanam, Sumatra. 



4. Opisthotropis typica. 



Helicopsoides typicus, Mocquard, Le Natur. 1890, p. 154, and Noim, 



Arch. Mm. (3) ii. 1890, p. 141, pi. ix. iig. 3. 

 Opisthotropis typica, Bouleng. Ann. 8f Mag. N. S. (6) vii. 1891, 



p. 343. 



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

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

 nasals small, triangular; a pair of praifrontals ; frontal large, 

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

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

 oculars ; three suboculars separating the eye from the labials ; 

 temporals 1 + 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 millim. ; tail 95. 



Mt. Xina Baloo, North Borneo. 



18. ISCHNOGNATHUS. 



Isehnognathus, Bum. Sr Bibr. Mim. Ac. So. xxiii. 1853, p. 468, and 

 Erp. Gin. vii. p. 606 (1854) ; Gunth. Cat. Col. 8n. p. 80 (1858) j 

 Jan, Arch. Zool. Anat. Phys. iii. 1865, p. 238. 



Storeria, Baird 8r Gir. Cat. N. Am. Rept. p. 185 (1853). 



Microps (mora Megerle), Hallow. Proc. Ac. Philad. 1856, p. 240. 



Tropidoclonion, Cope, Proc. Ac. Philad. 1860, p. 76, and Proa. US. 

 Nat. Mus. xiv. 1892, p. 666. 



Oora, Jan, I. c. 



Adelophis (Dugbs), Cope, Proc. Am. Philos. Soc. xviii. 1879, p. 266. 



Clonophis, Cope, Proc. U.S. Nat. 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. 



