138 TELLINID^E. 



within. The foot is long, broad, flat, large, white, pointed, 

 and geniculated, as in Tellina ; indeed, the animal is closely 

 allied to that genus ; the greatest difference is in the shell, 

 which, with the outward ligament of the Tellina, has also a 

 small internal cartilage fixed in an oblique cavity. The liver 

 is dark green, placed at the summit of the dorsal line. We 

 extracted the crystalline stylet and attritor, called by authors 

 the tricuspid membrane. 



It inhabits, sparingly, the coralline zone at Exmouth. 



The two following species have not occurred : 



S. TENUIS, Montagu. 



S. tennis, Brit. Moll. i. p. 323, pi. 17. f. 11. 

 S. INTERMEDIA? Thompson. 



S. intermedia ? Brit. Moll. i. p. 319, pi. 17. f. 9, 10 ; (animal) pi. K. f. 5. 

 We very much think that the S. intermedia is nothing 

 more than a variety of S. prismatica, being the result of 

 climate. 



SCROBICULARIA, Schumacher. 

 S. PIPERATA, Gmelin et Philippi. 



S. piperata, Brit. Moll. i. p. 326, pi. 15. f. 5 ; (animal) pi. K. f. 6. 

 Mactra compressa, nonnull. 



Animal suboval, compressed, pale yellowish-brown ; mantle 

 open, with a fringe only visible by the aid of a good lens ; the 

 siphons are nearly as long as the shell, separate from their 

 bases, of the same length, subcylindrical, tapering to the 

 extremities, which are truncate, without cirrhi, of a pale dirty- 

 brown, the effect of a fine epidermis. There is, on each side, 

 a single, subangular, pale yellow branchia, running obliquely, 

 I may say almost vertically, from the dorsal to the ventral 

 range, very finely pectinated on the outside, but more in- 

 tensely within ; the two palpi, on each side, are large, thin, 

 flat, very long, triangular, broad above, pointed at their ter- 

 minations ; they present the same characters as to colour and 

 pectination as the branchiae. 



This is strictly a littoral species, inhabiting the quiet muddy 



