122 A HANDBOOK FOR SOUTHPORT. 



Mactra stultorum. Very common and fine. Sometimes at 

 low-water, lying in groups of hundreds together, within 

 spaces of a few yards. The gulls break immense numbers 

 to get at the animals. 



Mactra solida. A few single valves have been found. 



Lutraria elliptica. Single valves are occasionally met with : 

 perfect shells very rarely. It is a large, oblong, rather 

 flat shell, gaping or open at the extremities. 



Tapes pullastra. Artemis liruta. A few single valves of the 

 two latter species have been found. Species that are so 

 rarely picked up, and then only in single valves, are, as a 

 rule, found attached to corallines. 



VENERID^E. 



Venus striatula. Common. Triangular. Looking at the shell 

 edgeways, it is heart-shaped, has highly raised concentric 

 lines, and is sometimes handsomely marked with rich 

 brown rays. 



Venus ovata. Very rare. Similar in shape to a cockle, but 

 small and white, and the sculpture much finer. 



Ludnopsis undata. Moderately common. A roundish shell, 

 white, slightly tinged with rust colour ; varies from a 

 quarter to three quarters of an inch in length and 

 breadth. 



CYPRINID;E. 



Cyprina Islandica. Perfect shells of this fine species are 

 rarely to be met with ; single valves not uncommon. 



CARDIAD.E. 



Cardium echinatum. A large species of the Cockle tribe, with 

 thick radiating ribs, bristling with tuberculous spines. 



