288 



LIFE BY THE SEASHORE. 



Shell wedge - shaped, 'j 

 smooth glossy, with I D 

 external ligament and j 

 deep sinus . . . J 



Shell compressed, rounded ^ 

 in front, angular and j 

 slightly folded behind, V Tellina 

 ligament external, pro- j 

 minent . . . . J 



Shell rounded, solid, with ^ 



concentric ribs and small V Venus 

 sinus . . . . J 



Shell oblong, beaks an- ^ 

 terior, margin smooth, 1- Tapes 

 sinus deep and rounded . ' 



Shell convex, triangular, 

 with radiating ribs, 

 notched margin and 

 fluted interior. Beaks 

 prominent, incurved 



(b) Shells gaping. 



Shell oblong, valves un- 

 equal, left valve the 

 smaller, with large carti- 

 lage process . . . . 



* Cardium 



Mya 



Shell oblong, two diverging \ T , lfrnr { n 

 cardinals in each valve . / Lutrana 



Shell elongated, cylindrical, ) , 

 margins parallel. .} Solen 



Shell rhomboidal, wrinkled, j Saxicava 

 truncated . . .J 



Shell white, opaque, with } 

 rows of prickles, acces- I 

 sory valves or shields j 

 present . . . .J 



PJiolas 



Margin strongly notched, 

 interior stained with 

 purple D. vittatus. 



/ Shell thin, glossy, semi- 

 \ transparent T. tenuis. 



f Shell triangular, inside 

 J margin notched, except 

 j at posterior side V. 

 \ striatula. 



{Shell solid and opaque, 

 marked by numerous 

 fine concentric bands 

 T. pullasf.ra. 



f Ribs 24 to 28, furrows nar- 

 \ row C. edulc. 



Shell oblong, twice as long 



as broad M. arenaria. 

 Shell oval, abruptly trun- 

 cated behind M. trun- 

 cata. 



i Shell compressed, elliptical, 

 ! brightly coloured L. 

 [ elliptica. 



/ Shell straight S. siliqua. 

 \ Shell curved S. cnsis. 

 f Shell small, about 1 inch 

 \ long S. rugosa. 



{Shells divided by furrow, 

 20 rows of prickles on 

 an terior side P. crispata. 

 Shell not divided, 25 to 30 

 rows of prickles P. Can- 

 dida. 



NOTE ON DISTRIBUTION. 



The Bivalves described in this chapter are, generally speaking, those 

 which may be expected to occur at all parts of our coast, so that little 

 can profitably be said as regards distribution. It is obvious that such 

 forms as the edible mussel and cockle cannot from their habits be 

 expected to occur, in any abundance at least, except where shallow, 



