352 



The following species, unknown to me, appears to be insufficiently 

 characterized : 



TROPIDONOTUS ANGUSTICEPS, Blyth, J. A. S. B. xxiii, 1855, 

 p. 295. 



Head narrow, not broader than the neck ; two to four prse- and 

 four or five postoculars. Ventrals 167-172 ; subcaudals 57-67. 

 Plumbeous above, uniformly spotted with black ; below whitish, 

 more or less varigated with black on the hinder half ; a V-like 

 mark on the nape, with the apex towards the occiput, becoming 

 obsolete in adults. 



Total length 41 inches ; tail 8'5. 



Hub, Assam and Arrakan. 



Genus HELICOPS, 

 Wagler, Syst. Amph. p. 170, 1830. 



Maxillary teeth about 20, posterior largest ; maudibular teeth 

 subequal. Head slightly distinct from neck ; eye moderate or 

 rather small, with round pupil ; nostrils directed upwards, in a 

 semidivided nasal ; a single internasal. Body rather stout, cylin- 

 drical ; scales keeled, in 19 to 23 rows, without apical pits; veutrals 

 rounded ; subcaudals in two rows. 



With the exception of the following, the species of this genus 

 inhabit Tropical America. Habits aquatic ; feeding on batrachians 

 and fishes. 



440. Helicops schistosus. 



Russell, 2nd. Serp. ii, pi. iv. 



Coluber schistosus, Daud. Rept. vii, p. 132. 



Tropidonotus schistosus, Sclikg. Phys. Serp. ii, p. 319 ; Cantor, J. A, 



S. B. xvi, 1847, p. 938 ; Dum. $ Bibr. Erp. Gen. vii, p. 596. 

 Tropidonotus mcestus and T. turgens, Cantor, P. Z. S. 1839, p. 54. 

 Atretium schistosum, Giinth. Rept. B. I. p. 273 ; Theob. Cat. p. 179. 

 Helicops schistosus, Jan, Icon. Ophid. 28, pi. ii, fig. 3. 

 Atretium schistosum, var. yunnanensis, Anders. An. Zool. Res. 



Yunnan, p. 822. 



Eye moderate ; rostral just visible from above, forming a narrow 

 suture with the internasal ; frontal much longer than its distance 

 from the end of the snout, shorter than the parietals ; loreal deeper 

 than long ; one prseocular ; two or three postoculars ; temporals 

 2 + 2; upper labials 8 or 9, third and fourth or fourth and fifth 

 entering the eye ; 4 or 5 lower labials in contact with the anterior 

 chin-shields, which'are shorter than the posterior. Scales more or 

 less distinctly keeled, in 19 rows. Ventrals 129-151 ; anal divided; 

 subcaudals 55-85. Olive-brown above, uniform or with two 

 series of small black spots along the back ; a more or less distinct 

 dark lateral streak; upper lip, outer row of scales, and lower 

 surfaces yellowish. 



Total length 2| feet ; tail 7 inches 



