1918.] N. Annandale: Molluscs nf tJie InU Lake. 115 



deposits on the He-Ho plain. Each of these phases was constant in 

 the locaHty or precise deposit in which it was found. 



Melania terebra, Benson. 

 Plate xii, fig. 9. 



1836. Melania Terebra, Benson, op. cit., p. 747. 



1876. Melania terebra, Hanley and Theobald, op. cit., pi. Ixxi, figs. 8, 9. 



A few living shells were found in the Yawnghwe river with M. 

 tuberculata. They agree well with Hanley and Theobald's figures. 

 The species is known from Sylhet and north-eastern Assam. 



Melania baccata (Gould). 

 Plate xii, figs. 3, 3a, 4 — 7. 



1915. Tiara {Melanoides) baccata, Preston, op. cit., p. 26. 



Melania baccata is a species, or possibly a group of species, that 

 seems to have become differentiated on the Shan Plateau and in Upper 

 Burma into a large nvimber of well-defined races. To what extent 

 all these races are constant we do not yet know, but the only one found 

 living or subfossil in the Inle and He-Ho basins, though it varies some- 

 what in sculpture and is plastic in size, is, nevertheless, remarkably 

 constant in the shape of the shell, in which it differs from any form 

 as yet described. I have thought it best, in view of our ignorance of 

 the anatomy and our scanty knowledge of the distribution of the various 

 " varieties," to call this form a subspecies, by which I mean a local 

 race. 



subsp. elongata, nov. 



In shape the shell is long, narrow and tapering. When complete 

 it has 11 or 12 whorls, but the first two are usually eroded. The aper- 

 ture is very narrow and nearly oval ; the lip is considerably produced 

 forwards and the columella is less bent than in most forms of the species. 

 The sculpture is always well developed ; on the last three w^horls there 

 are usually three spiral rows of tubercles joined together by ridges in 

 such a way as to form a very regular reticulation. On the body-whorl 

 the uppermost row of tubercles is situated close to the upper edge. 

 There are three well-developed simple or superficially somewhat un- 

 dulated ridges beneath the lowest row. Sometimes, however, there are 

 only two rows of tubercles on this and the preceding whorl. The 

 shell is thin ; the epidermis is dark-brown or dull olivaceous-green ; 

 internally the surface is white and somewhat opalescent, as a rule 

 with several deep-brown spiral bands. 



At least two phases of this race can be distinguished : — (a) With 

 a very large shell, when complete nearly 80 mm. long and 26 mm. in 

 greatest breadth, and (6) with a much smaller shell not exceeding 

 50 mm. in length and 17 mm. in breadth. Of the first phase we found 

 only a few specimens, all living in a swamp on the He-Ho plain. The 

 second phase is abundant in the Yawnghwe river in a living condition 

 and is also common subfossil in peaty and calcareous deposits on the 

 He-Ho plain. 



