2o8 H. B. Preston : New species of Shells. [Vol. II, 



Donax tiesenhauseni, sp. nov. 



Shell wedge shaped, yellowish, rayed with greyish purple, 

 sculptured with very fine, concentric striae and fine nearly obsolete 

 transverse striae, both becoming so much coarser posteriorly as to 

 give that part of the shell a cancellate appearance ; anterior side 

 produced, obtusely rounded ; posterior side abruptly truncate ; 

 anterior lateral margin gently, concavely sloped; posterior lateral 

 margin arched ; ventral margin straight ; umboes white. 



lyong. . . . . 8*5 mm. 



Lat. . . . . 13 



Habitat — Andaman Islands. 



Donax trigonalis, sp. nov. 



Shell almost trigonal, convex, very truncate, pale bluish 

 flesh colour, tinged posteriorly with livid purple, partly covered 

 with a thin, yellowish periostracum, sculptured with fine concentric 

 lines of growth and posteriorly with fine longitudinal striae which 

 become gradually coarser, giving to this part of the shell a cancellate 

 appearance ; anterior lateral margin sloped ; posterior margin des- 

 cending very abruptly ; ventral margin rounded; umboes large, but 

 not prominent; interior of shell pale flesh colour, changing to 

 blackish purple in places. 



Ivong. .... . . 9-5 mm. 



Lat. . . . . II ,, 



Habitat — Andaman Islands. 



This species differs from Donax mcarnatus , Chem., to which it 

 appears to be most nearly related, by its more truncate form, more 

 rounded ventral and straighter posterior margins. 



Psammobia obtusa, sp. nov. 



Shell ovately transverse, pale mauve, blotched and mottled 

 with a darker shade of the same colour and rayed with interrupted 

 bands of reddish violet, sculptured throughout with fine, con- 

 centric striae and oblique ridges which appear as irregular, waved 

 plications posteriorly ; posterior side obtusely angled ; anterior side 

 rounded ; umboes central ; interior of shell mauve throughout, 



Long, . . : . . 24'5 mm. 



lyat. . . . . 42 ,, 



Habitat — Andaman Islands. 



The present species at first sight recalls P. ornata, Desh. ; it is, 

 however, broader, shorter and more blunt on both sides than is that 

 species, the riiauve colour also easily distinguishes it from P. ornata, 

 which is of a yellowish white colour ; the coloration of the interior 

 is also remarkable. 



