DoNAx. MOLLUSCA. DONA( ID^E. 433 



Mactra alba, JVood, Linn. Trans, vi. \7'i. t. xvi. f. 9-12. Ligula Boy- 

 sii, Mout. Test. Brit. 98. t. iii. f. 7 — Ami)hidesma Boysii, Turl. Biv. 

 Brit. 53. t. V. f. 4, 5. — Sandy shores, frequent. 

 Length half" an inch, breadth three-quarters, glossy, pellucid ; slopes from 

 the beak on both sides; the ventral margin rather suddenly rounded; a sin- 

 gle umbonal denticle in each valve, and a large lateral tooth on each side in 

 one valve ; it is readily distinguished by its shortness and pellucidity. 



471. A. tenue. — Subtriangular, equilateral with a rounded 

 ventral margin, 



Ligula tennis, Mont. Test. Brit. 572. t. xvii. f. ?•— A. tenue, Tiirt. Biv. 



Brit. 53. — South coast of England. 



Length a quarter of an inch, breadth a little more ; white, concentrically 



wrinkled, comjjressed, beaks produced, central ; hinge with one bifurcated 



tooth, and a remote lateral one in one valve, and a single plain tooth in the 



other. 



DONACIDyE. 



Gen. CXIX. DONAX. — Transversely subtriangular, retraK- 

 ly short and truncated ; hinge with two teeth in both 

 valves ; lateral teeth rather remote. 



* Inner margin cremdated. 



472. D. truncidus. — Shell with numerous minute simple 

 longitudinal stria?, becoming obsolete towards the antcal extre- 

 mity. 



Tellina intus ex viola purpurascens, in ambitu serrata, List. An. Aug 

 190. Conch, t. ccclxxvi. f. 217 — D- trun. Linn. Syst. i. 1127. Penn. 

 Brit. Zool. iv. 93. t. Iv. Mont. Test. Brit. 103. furt. Biv. Brit. 123. 

 —Sandy shores, common. 

 Length five-eighths of an inch, breadth one inch and a quarter ; a yellow- 

 ish-white cuticle, inside purple, retrally obliquely truncated, the anal angle 

 rounded ; anteally compressed, rounded, with the dorsal margin nearly 

 straight. 



473. D. dcnticulata. — Shell with numerous fine punctured 

 longitudinal striae. 



Tellina purpurascens, List. Conch, t. ccclxxvi. f. 21 «. — D. dent. Lim*. 

 Syst. i. 1127. Penn. Brit. Zool. iv. 93. Mont. Test. Brit. 104. Tiirt. 



Biv. Brit. 124 English shores, rare. 



Length about half an inch, breadth an inch; whitish, rayed with purple- 

 It is more suddenly truncated retrally than the preceding species, and rough 

 with ridges. 



** Inner margin cMirc. 



474. D. complanata. — Transversely elongated, smooth, with 

 a longitudinal white band. 



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