No. I (1917) 



EDIBLE MOLLUSCS 



25 



is pretty frequent along the island beaches near Pamban and is 

 fished and treated for food in the same way as Circe gibha ; it grows 

 to a length of 34 mm. ; the shell, sculptured with bold concentric 

 ridges, is white in colour, covered partially with a dirty yellow 

 skin of periostracum (Fig. 8). The pretty little Sevala-matti 

 (Mactra corbiculoides Desh.) tinted a deep violet colour within, is 

 equally common in the same localities ; its smooth shell is distinctly 

 trigonal in outline, usually about 30 mm. in length, with deeply 

 concave valves which are thus able to give accommodation to a 

 body relatively much larger than is contained within the shallower 

 valves of the Kakkamatti. Its colour is most distinctive ; exter- 

 nally a bluish-grey with purplish blue colouring showing through 

 at the umbo and usually another similar colour band within the 

 margin ; internally the whole surface is characteristically tinted 

 violet. When partially bleached, the colour fades to a warm pink, 

 whence the local name of Scvala matti (red matti). Like all 

 Mactrids a portion of the ligament is contained in a centrally 

 placed deep pit or fossette within the hinge and immediately 

 under the umbo (Fig. 9). 



Fig. 9. — Sf.vala matti (Mactra corbkiiloides). 

 Inner view of hinge on the right. 



A handsome inflated form of Tapes (Tapes ceylonensis Sow.), 



called Vazhukkumatti in the neigh- 

 bourhood of Pamban is fished with 

 the foregoing. It has a superficial 

 resemblance to the backwater clam 

 Meretrix easta, being about the same 

 size, shape and colour (Fig. 10); it 

 differs however in having pale 

 radiating bands of darker tint on 

 each valve running from the umbo 

 Fig. ic-Vazhikkumatti (7a/.^s ^^ margin and instead of having 



