268 N. ANNANDALE. 



contained 3f in the total height and the height of the mouth is a Httle more than ij 

 times its maximum diameter. 



Type- specimen (from the Andamans.) No. Miif ^^ Z.S.I. (Ind. Mus.). 



Geographical Distribution. Andaman Is., Bay of Bengal ; Chilka Lake, Orissa and 

 Ganjam district, Madras ; ? Cochin backwaters, west-coast of India (young shells only 

 examined) ; Trincomah, Ceylon; the Maldive Islands; Bombay, and Penang. 



The species is distinguished from Lamarck's Purpura carinifera not only by its 

 usually smaller size, its duller colouration and narrower and smaller shell-aperture, 

 but also by the curious change in the spiral above the body-whorl. This is a con- 

 stant feature in a large series, recent and subfossil, from the Chilka Lake and is 

 equally well shown in the type-specimen/ a single shell from the Andamans. From 

 Bomba}^ and other localities I have seen shells of both species, but have no informa- 

 tion as to the circumstances in which they were found. 



The type-specimen is a little larger, broader and thinner than those from the 



Chilka Lake and has the sculpture much sharper. I can detect no definite difference 



between recent and subfossil shells in the latter locality, but the subfossil shells are 



usually smaller. A very large but much worn specimen from the Maldives is 65 mm. 



high b}^ 48 mm. broad. 



PELKCYPODA. 



I'ani. Arctdae. 



Area granosa, L. 



igi6. Area (Aiiadara) ^i',inosif. Annaiidale and Kemp, Mem. Ind. Mits., V, p. 350. pi. xvi, 

 figs. 3-6. 



1918. Area granosa. Annaiidale, Me)ii. As. Soe. Bengal. VI, p. 318. pi. x, figs, 14-17. 

 As is pointed out in the papers cited, the race of Area grauosa that now lives in 

 the main area of the Chilka Lake, or did so in 1914, differs greatly from the one found 

 subfossil on Barkuda and at various places on the shores of the lake. In the collec- 

 tion of the Indian Museum, which includes a considerable number of specimens of 

 the species from Japan, China and the Malay Peninsula as well as from the Indian 

 coasts^ I have found examples of at least four distinct types, which I shall call for 

 the present types A, B, C and D. * 



Type A. This type is represented only from the Andaman and Nicobar Is. in the 

 Bay of Bengal. Its mo.st characteristic feature is the great size of the shell, which 

 is .sometimes over 75 mm. in breadth. The shell is moderately thick. The breadth 

 is distinctly but not much greater than the height and the diameter of the two 

 valves together is a little less than the height. Thus in a .shell from the Andamans 

 74 mm. in breadth the proportions are height to breadth i : 1-15, diameter to breadth 

 i: I], diameter to height i: 112. The shell is distinctly inequilateral, though 

 much less so than in some species of the genus, and is as a whole transversely oval. 

 The periostracum is blackish and the ribs are divided into small flat ridges by almost 

 equidistant, rather deep transverse grooves. 



^ The notch in the outline produced by the change of direction is concealed in the photograph here reproduced 



jy one of the processes on the body-wliorl. 



