414 VENERID^. 



the shape of the shell, but is prolonged anteriorly into two 

 smooth slender completely-united tubes, forming a single 

 siphonal process. The anal tube is much smaller than the 

 branchial, and its orifice is separated only in the slightest 

 and almost imperceptible degree. Mr. Clark has observed 

 ten cirrhi, and intermediate shorter ones around the 

 branchial orifice, and ten around the anal. In several 

 specimens which we have examined we found the cirrhi of 

 the branchial orifice rather more numerous, but very short 

 and inconspicuous, and could only distinguish them as den- 

 ticles on the anal margin. Both tubes are of a pale sul- 

 phur-yellow, in some examples slightly tinged with rose 

 around their extremities. They may be extended to a 

 length very nearly equalling the breadth of the shell. The 

 mantle is freely open, and is of a yellowish-white colour ; 

 it is fringed by cirrhi or fimbriations, which are fasciculated 

 so that it appears to be sinuous, and bordered by a series of 

 little tufts. The foot is large, fleshy, white, linguiform, and 

 geniculated. Mr. Clark has observed that the branchiae on 

 one side are very unequal, the upper being much shorter 

 than the lower. The animal in confinement is rather 

 sluggish. 



This is one of our commonest shells, occurring every- 

 where upon our sandy coasts, and ranging to the greatest 

 depths as yet explored in the British seas. Some of its 

 numerous varieties, especially that termed sulcata by Cap- 

 tain Brown, are however rare. It is so generally distri- 

 buted that to sj)ecify localities would be to enumerate al- 

 most every point explored where the bottom was sand or 

 sandy mud. The form generally thrown up on the shore 

 lives in sandy tracts near low-water mark, but the lamel- 

 lated kinds inhabit deeper water. Specimens dredged by 

 Mr. M 'Andrew in depths between eighty and one hundred 



