418 BULLETIN 58, UNITED STATES NATIONAL MUSEUM. 



Genus DISTEIRA" Lacepede. 



1803. Hydrophis Daudin, Hist. Nat. Kept., VII, p. 372 (part; not of Latreille, 



1802). 



1804. Disteira Lacepede, Ann. Mus. d'Hist. Nat., Paris, IV, p. 210 (type, I). 



doliata). 

 1804. Leioselasma Lacepede, Ann. Mus. d'Hist. Nat., Paris, IV, p. 210 (type, L. 



striata). 

 1830. Enhydris Wagler, Nat. Syst. Amph., p. 166 (typ(?, Hydrophis cyanodnctus) 



(not of Latreille, 1802). 

 1834. Microcephalophis Lesson, in Belanger's Voy. Indes Orient., Rept. (p. 320); 



Atlas, Rept., pi. iii (type, M. gracilis). 

 1842. Liopula Gray, Zool. Misc., p. 60 (type, Hydriis (iracilis Shaw). 

 1842. Liopola Gray, ZooL Misc., p. 60 (err. typogr.). 

 1842. Aluria Gray, Zool. Misc., p. 61 (type, A. ornata). 



1848. Noterophis Gistel, Naturg. Thierr., p. ix (substitute for Enhydris Wagler). 



1849. Chitvlia Gray, Cat. Sn. Brit. Mus., p. 56 (type, Ch. mornata). 

 1849. Kerilia Gray, Cat. Sn. Brit. Mus., p. 57 (type, K. jerdonii). 



1852. Thalassophis Schmidt, Abh. Naturw. Ver. Hamburg, II, Pt. 2, p. 75 (substi- 

 tute for Hydrophis Daudin). 

 1887. Distira Cope, Bull. U. S. Nat. Mus. No. 32, p. 61 (emendation). 



The large central group of Hydrid snakes, about 40 species, has 

 been gathered into two genera by Boulenger according to whether the 

 maxillary teeth following the first pair of poison fangs are grooved 

 {Disteira) or "solid " ( Microcephalophis = Hydrophis Daudin, 1803, not 

 Latreille, 1802). Recently some doubt has been thrown on the 

 validity of this separation, inasmuch as Mr. West, in a typical 

 Disteira, viz, D. cyanocincta, found that "the first two or three only 

 of these teeth showed any indications of a groove." ^ 



Relying, however, on the division established by Boulenger, I 

 identified some of my specimens in which no grooved teeth were 

 observable under a magnification of 10 diameters, as Microce])halophis 

 melanocephalus.'' Three years later some similar snakes came under 

 my notice, which, investigated by the same means, showed distinct 

 grooves in the maxillary teeth, and as their other characters did not 

 correspond to those of any other Disteira, I described them as a new 

 species, D. orientalis.'' While preparing detailed descriptions for the 

 present work, however, I was forcibly struck by the fact that in all 

 external characters the two species were absolutely identical. ]\lr. 

 West's experience with D. cyanocincta and other parallel cases with 

 various opisthoglyph snakes then occurred to me. The specimens at 

 my command were consequently subjected to much greater magni- 

 fications, with the result that I find all the teeth grooved in all the 

 specimens examined by me. To see the groove plainly it was often 



a From 5ts, double; drelpa, keel. 



b Proc. Zool, Soc. Londim, 1895, p. 823, pi. xlvi, fig. 8. 

 cjourn. Sci. Coll. Tokyo, XII, Pt. 3, 1898, p. 224. 

 d Proc. Biol. Soc. Washington, XIV, 1901, p. 191. 



