VENUS. 65 



united, except near the openings, which are fringed. 

 It has not, like Ta]ieSy a byssus for anchoring. 

 III. Yenus. — The Vemis has not a separate lateral tooth in 

 the hinge of its shell, but three diverging cardinal teeth. 

 The shells vary considerably in shape and colouring. 

 The larger and more beautiful Venerea belong to tropical 

 climates, but we have several on our own coasts which are 

 very pretty in their way. Their habits vary very much, 

 particularly in respect to the greater or lesser depths of 

 ocean under which they live, some being almost littoral, and 

 others living in the deep recesses of the sea : those that lie 

 furthest out of sight are, however, destitute of colour. 

 V. verrucosa has a thick, round shell, with strong, coarse 

 concentric ridges, the ridges crossed by oblique dis- 

 secting lines, which cut them up into knobs or " warts " 

 on each side. Animal pale yellowish- white. 

 V. carina : shell flatter, but round ; ribs rounded in front, 

 flattened or laminated behind, and 7iot dissected when 

 young; it is delicately rayed. 

 V. striatula : shell rather triangular, sometimes marked by 

 zigzag lines, with concentric ridges numerous, more or 

 less flattened at the back, with fine brown lines on the 

 flattened dorsal area. Plentiful on our sandy coasts. 



