SERPENTES. 129 



Known from a number of the Moluccas, and from Timor-Laut. It is found 

 upon the Sanghir Islands; and hence we may suppose that it is likely to occur 

 in Celebes and even perhaps in the PhiUppines. 



Hydrus platurus (Linn^:). 



Linn£, Syst. nat., ed. 12, 1766, 1, p. 391. Boulenger, Cat. snakes Brit, mus., 1896, 3, p. 266-268. 

 (Data on variation). Stejnegbr, Bull. 58, U. S. nat. mus., 1907, p. 439-442 (Synonymy and 

 description) . 



Type locality: — unknown. 



This form, one of the most widely distributed of reptiles, presents a per- 

 plexing problem to the zoogeographer. In the series of specimens available for 

 study here, and with the data which Boulenger {loc. cit.) supplies, nine easily 

 distinguishable color-phases may be recognized. To show, moreover, what 

 slight relation these phases bear to the distribution of the snake, it may be added 

 that six -of these forms occur in and about the Bay of Panama. Stejneger 

 {loc. cit., p. 440) remarks that there seems to be "a certain regularity" in the 

 distribution of these "color varieties." "Thus the ordinary black-backed form," 

 he says, "seems to be almost exclusive in the Pacific Ocean; spotted individuals, 

 such as the one figured in Fauna Japonica, plate viii (from the west coast of 

 Borneo), appear to occur mostly in the Indian Ocean. All the specimens from 

 eastern China, Formosa, Riu Kiu, and Japan, so far as the records show, are of 

 the black-backed form." However, this same "black-backed form," which 

 ~ in its simplest coloration Boulenger calls E, is known to occur from Madagascar 

 to the eastern coast of Central America. Not so with the "spotted form," 

 which Boulenger calls A. This appears to be rather definitely confined to the 

 waters of the East Indian Archipelago, and may be recognized as a geographical 

 race. 



Hydrus platurus ornatus (Gray) . 



Color: — yellowish, dorsally with brown, black-edged cross-bands; ventrally 

 with black bars running up the sides, and alternating with the dorsal bands. 



This form is the most distinct of any of the color-phases. It shows little 

 relation to the others, and does not seem to intergrade with them, unless we 

 consider the rare and little-known var. maculata Jan an intermediate phase. 



Gray (Zool. misc., p. 60) in 1842 recognized this as a distinct species, and 

 recorded it from India. In 1896 Boulenger {loc. cit., p. 267) recorded a specimen 

 from Borneo as "Type of P. ornata" ; the only other specimen of this form in 

 the British museum at that time was one from "India?." It would be interest- 

 ing to know whence the type really came! Dumeril and Bibron (Erpet. gen., 



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