Heart-Cockle and Fresh-water Cockle 



93 



fresh-water species, so we must at times turn from 

 the seashore to the river and pond. 



The animal in tlie first genus — Astarte — has an 

 almost round body, flattened from the sides. Tlie 

 lips are large ; the mantle thick, not fringed with 

 tentacles, but part of it forms a short excretory 

 siphon behind. The foot is conical and small, though 

 tolerably powerful. The shell is more or less tri- 

 angular and thick, somewhat flattened, with concentric 

 furrows. It is covered by a thick yellow or brown 

 epidermis, and has prominent beaks. In front of the 

 beaks will be found a dark depression called the 

 lunule, found in many other genera of bivalves, and 

 here heart-shaped or lance-shaped. Internally the 

 valves are furnished with three central teeth 

 (cardinals) below the beak, and a ridge-like tooth 

 (lateral) on either side. There are 

 three native species. 



The Furrowed Astarte-shell (A. sul- 

 cata) has from 24 to 40 thick ridfres, 

 and is white beneath the brown epi- 

 dermis. The broad hinge-plate bears ^'"°^'^ ^'''''' 

 three cardinal teeth, one small and indistinct, two 

 large ; laterals indistinct. The margin is thick and 

 notched within. It partially embeds 

 itself in sand and mud all round our 

 islands in water from 7 to 145 

 fathoms deep. It is by no means 

 active, getting its microscopic food in 

 Furrowed Astarte- plenty without the ncccsslty for pur- 

 suing it. The Flat Astarte-shell (A. 

 compressa) is only about one-half the length and 

 breadth of the last named, and may be distinguished 



