300 BULLETIN 58, UNITED STATES NATIONAL MUSEUM. 



Genus ENHYDRIS" Latreille. 



1802. Enhydiis Latreille, Hist. Nat. Rept., IV, p. 200 i type, E. cxndea^Hydrus 

 cnhijdris Schneider) (not of Merrem 1820). 

 - 1830. Hypsirhina Wagler, Syst. Anaphib., p. 169 (type, //. aer). 



1842. Ferania Gray, Zool. Miscell., p. 67 (type, II. sieboldii). 



1843. Ilypsiscopus Fitzinger, Syst. Rept., p. 25 (type, H. plumbea). 

 1843. Pythomorphus Fitzinger, Syst. Rept., p. 25 (type, H. sieboldii). 



1853. Eurostus Dumeril, Prodrom. Class. Ophid., p. 102 (type, E. dussmnierii). 

 1853. Trigonurus Dumeril, Prodrom. Class. Ophid., p. 103 (type, //. sieboldii). 



The authors who employ the generic name, ' ' Enhydris, Merrem, 

 1820," for two of the Hyclrid snakes which should correctly stand as 

 Lapemis, seem to have overlooked entirely the fact that Latreille, 

 as early as 1802, established the genus Enhydris for an entirely dif- 

 ferent set of snakes, embracing all Schneider's species of Hydrus, 

 from //. caspius on. This name, which can not be discarded, as it 

 is not a synonym of any name previously given, must have for type 

 one of the six species enumerated by Latreille, and as neither he 

 nor any of his successors have designated a tyi^e for the name, we 

 are obliged to resort to the method of elimination. The last species 

 mentioned by Latreiile, Enhydris dorsalis, is of dubious application. 

 The third, Enhydris ryncJiops, is the type of Daudin's Hurria (1803), 

 Goldfusz' Strephon (1820), and Cuvier's Cerberus (1829), while three 

 other species, viz, E. caspius, piscator, and palustris belong to the 

 genus Natrix {Tropidonotus) . A single species is thus left as type, 

 viz, Enhydris cxrulea, which is Schneider's Hydrus enhydris. This 

 species, or rather a synonym of this species, was afterwards (1830) 

 made the type of Hypsirhina, and there can be no doubt but that 

 the latter name will have to give way to Enhydris Latreille. The 

 same result is obtained by those who would fix the type by employ- 

 ing the "principle of tautonymy." 



Two species have been recorded as occurring in Formosa and for 

 that reason are here included. They may be distinguished as fol- 

 lows : 



a' Scales in 19 rows; supralabials 8; ventrals less than 150 E. plumbea, p. 300. 



a- Scales in 21 rows; supralabials 7; ventrals more than 150 E. bcnnettii, p. 302. 



ENHYDRIS PLUMBEA ?> (Bole). 



1827. Homalopsis plumbea Boie, Isis, 1827, p. 550 (type-locality, Java). — 

 Hypsirhina plumbea Gray, Zool. Misc., 1842, p. 66. — Guenther, Rept. 

 Brit. India, 1864, p. 280 (Java to Formosa).— Jan, Icon. Ophid., livr. 30, 

 1868, pi. v, figs. 2-3 (Java).— Boettger, Offenbach. Ver. Naturk. 24-25 

 Ber., 1885, pp. 123, 151 (China); Ber. Senckenberg. Naturf. Ges., 1894, 

 p. 134 (Hainan).— BouLENGER, Cat. Snakes Brit. Mus., Ill, 1896, p. 5 

 (Formosa; China; Siam; Malay Peninsula; Java). — Wall, Proc. Zool. 



« From evvSpti, a water snake. 

 '> Signifying lead-colored. 



