Wedge-shells^ Venus-shells^ and Cockles 139 



tervenino- furrows being continued riolit to tlie 

 margins of the shell, those of the two valves inter- 

 lock, fitting in a very accurate manner. There are 

 one or two cardinal teeth in each valve, and a strono' 

 lateral on either side at some distance from the 

 cardinals. The gills are long and mucli folded back, 

 the siphons rather long, the foot large, long, and 

 cylindrical, the mantle - margins jagged. These 

 mollusks live in sand and mud, from low water to a 

 considerable depth, and by means of their foot can 

 rapidly sink into or rise above it. Pigment spots 

 serving as visual organs are scattered over the 

 margins of the mantle and over the tubes. 



The Spiny Cockle or Red - nose {Cardhmn 

 acideatuin) is the largest of our native species, and 

 measures as much as 3 inches across. The valves 

 are somewhat thin and glossy, covered by about 

 20 strong broad ribs that radiate from the beaks 

 and bear a number of stout curved spines whose 

 points are directed backwards. The colour is 

 yellowish tinged with red. The animal is coloured 

 bright red, and the red foot, which gives it the 

 popular name of Red-nose, is long and awl-shaped. 

 It is found in deep water along sandy shores, chiefly 

 in South Devon ; at Weymouth, Guernsey, and Dublin 

 Bay. The Prickly Cockle {C. ecJdnatitm) is not so 

 large as the foregoing, being little more than 2 inches 

 across ; but the shell is more solid, has a duller surface, 

 and a less oblique curve to the front margin. The 

 radiating ribs bear short, stout, triangular spines, 

 curved backwards. The colour is yellowish white, 

 stained with red. The animal varies in colour from 

 white to pink ; the foot is finger shaped, with a flesh- 



