15. HYDRID.'H 



Genus 46. Hydrus 



Hydrus Schneider, Hist. Amph., Vol. I, 1799, p. 123 (type, bicolor). 

 Hydrophis Latreille, Hist. Nat. Rept., Vol. IV, 1802, p. 193. 

 Pelamis Daudin, Hist. Nat. Rept., Vol. VII, 1803, p. 357. 

 Pelamys Wagler, Syst. Amph., 1830, p. 166. 

 Elaphrodytes Gistel, Naturg. Thierr., 1848, p. IX. 



The body is rather short, somewhat compressed, with 

 strongly compressed, short, oar-shaped tail. The head is 

 rather narrow and much depressed with long, broadly round- 

 ed snout. The nostrils open upward in the large nasal plates 

 on top of the snout. The head plates are large. There are 

 no internasals. The scales on the body are hexagonal or 

 quadrate, juxtaposed. There are no enlarged gastrosteges. 

 The eyes are small with round pupils. 



206. Hydrus platurus (Linnaeus) 

 Bicolor Sea-Snake 



Anguis platura Linnaeus, Syst. Nat., iied.. Vol. i 1766, p. 391 (no 



type locality). 

 Hydrus bicolor Schneider, Hist. Amph., Vol. I, 1799, p. 242 (no type 



locality). 

 Pelamis bicolor Daudin, Hist. Nat. Rept., Vol. VII, 1803, p. 366; Cope, 



Bull. U. S. Nat. Mus., No. 32, 1887, p. 87. 

 Hydrus platurus Boui.enger, Cat. Snakes Brit. Mus., \'o\. Ill, 1896, 



p. 267; Stejneger, Bull. U. S. Nat. Mus., No. 58, 1907, p. 439; 



Mc Lain, Contributions to Neotropical Herpetology, 1899, p. 5; 



Mocquard, Nouv. Arch. Mus. Hist. Nat., Paris, Ser. 4, Vol. I, 



1899, p. 330; Mocquard, Miss. Sci. au Mex., Pt. Ill, Rept., 1908, 



P- 930- 



Description. — Head depressed, flat-topped with long 

 broad snout. Temporal regions not swollen. Rostral plate 

 large, somewhat broader than high, bounded behind by 

 nasal and first labial plates. Plates on top of head are a 

 pair of very large nasals, a pair of prefrontals, a large fron- 

 tal, supraocular of each side, and a pair of large, long parie- 



