1807.] Contributions to Indian Malacology. 71 



roots of plants. The same species abounds in mud, amongst stones, 

 in Bombay harbour, and is collected for food by the natives. 

 No. 41, Scaphula deltse, n. sp. PI. III., fig. 7-10. 



Testa tunuda, perelongato-rJiomboidea, sub epidermide crassd, fused, 

 postice radiatim liratd albida, lineis minutis elevatis confertissimis 

 decussata, ante carinam eostd unicd lata, planulatd, aliquando obsoletd, a 

 natibusad marginem decurrente, munita, intus ccerulescens, antice rotun- 

 data, postice oblique truncata, mavgine ventrali antice concexd, postice vix 

 concavinscidd (tested junior is recta). Carina per elevata, acuta, vulvas 

 in paginas duces dividens, untied tumidd, posticd concavd. Area 

 nitida, sub lente striatula, Ugamento rhombeo solum antice induta. 

 Denies cardinales postici breves, obliqui, ab extremitate remotiusculi. 



Lett. 10 long 3J alt. 6£. 

 >j 8 „ 3 ,, 5. 



Shell very tumid, elongately rhomboidal, (the ventral and dorsal 

 margins being parallel as in S. celox) covered with a thick, dark epi- 

 dermis, which is rather rough and radiately ribbed behind the keel. 

 Beneath the epidermis the shell is white, and decussately very minutely 

 sculptured, one flat broad rib, scarcely raised, and occasionally obsolete 

 in old' specimens, passing from the umboncs to the margin just in front 

 of the keel. This is scarcely distinguishable until the epidermis is 

 removed. The valves are bluish within, rounded in front, obliquely 

 truncated at the posterior margin ; the ventral margin is convex an- 

 teriorly, subconcave posteriorly, being straight for the greater part of 

 its course in young shells, but' becoming slightly concave, at the spot 

 where the byssus passes out, in old specimens. The keel is very high 

 and sharp, separating the valves into two subdivisions, the anterior of 

 which is tumid, the posterior concave. The area is polished and stria- 

 ted rather obliquely, the ligament diamond-shaped and covering only 

 the anterior portion, about \ to J the length, of the area. The hinge 

 teeth are oblique, but less so than in either S. celox or S. pinna, and 

 the posterior teeth are much farther from the extremity of the shell 

 than in either of those species. 



The great distinction between this species and the other two pre- 

 viously described is in the far greater tumidity of the valves, which 

 are nearly twice as broad in their diameter from side to side (of the 

 closed valves) as they are from the dorsal to the ventral margin. 

 The proportion of the two diameters in the present species averages 



