16 



p. 377. Mont. Test. Brit., vol. 1, p. 99. L. V. Flem' 

 Brit. An., p. 464. The separate valves are found thinly 

 scattered along all our coasts. 

 L. HIANS. Mactra H. Mont. Test. Brit., vol. 1, p. 101. 

 Mya oblonga, Turt. Lin. L. H. Flem. Brit. An., p. 465. 

 Rare or local. Montagu found it not uncommon in the 

 river between Truro and Falmouth. 



MACTRA. 



GENERIC CHARACTER: Shell transverse, the sides 

 unequal ; the form subtriangular, gaping very little at the 

 sides; beaks prominent. One compressed, grooved, car- 

 dinal tooth in each valve, with an adjoining pit projecting 

 inwards ; two compressed, entering, lateral teeth, near the 

 hinge. Ligament internal, inserted in the cardinal pits. 



* M. SOLIDA. Turt. Lin. Pen. Brit. Zo., vol. 4, pi. 50, 

 fig. 43. Stew. Elem., vol. 2, p. 377. Mont. Test. Brit., 

 vol. 1, p. 92. Flem. Brit. An., p. 26. Abundant along 

 our southern coast. 



On the beach at Helford, near Falmouth, I obtained a 

 complete 'shell and two separate valves of, what must be 

 considered, a separate species or a variety of the above, as 

 future research shall determine. It is of the ordinary size 

 and appearance of the milk white specimens of M. Soiida ; 

 but from each umbo proceeds to the posterior margin a deep 

 channel, which forms an indentation at their place of meeting. 

 I had no opportunity of examining the animal. 



* M. TRUNCATA. M. Subtruncata. Mont. Test. Brit., 

 vol. 1, p. 93. M. Stultorum. Pen. Brit. Zo., vol. 4, pi. 

 52, fig. 42. Stew. Elem., vol. 2, p. 377. M. T. Flem. 

 Brit. An., p. 427. I have found it larger than the last 

 named species ; frequenting similar situations, but less 



. abundant. 



M. GLAUCA. Mont. Test. Brit., vol. 2, p. 571. Flem. 

 Brit, An., p. 428. Found by Miss Pocock on Halesands, 

 under Lelant. 



* M. STULTORUM. Turt Lin. Tellina Radiata (in 

 Montagu's opinion) Pen. Brit. Zo., vol. 4, pi. 49, fig. 30. 

 M. S. Mont. Test; Brit., vol. I, p. 94. Stew. Elm. vol. 2, 

 p. 376. Flem. Brit. An., p. 427. Not common on the 

 eastern shores ; but occurring on the north and soulh 

 coasts, and at Pentuan in abundance. 



M. DEALBATA. Mont. Test. Brit., vol. 1, p. 95. Flem. 



Brit. An., p. 428. Scarce. 

 M. MINUTISSIMA. Goodallia M. Flem. Brit. An., 



p. 429. 



AMPHIDESMA. 

 GENERIC CHARACTER: The shell transverse, sides 

 unequal, rounded, sometimes gaping a little ; hinge with 



