154 WORMS. TESTACEA. 40. Mactra. 



grooves; the margin slightly crenate : beak central, pointed, turn- 

 ing to one side. 



235. C. corneum. Suborbicular, convex, thin, pellucid, 

 with line concentric striae, one of which is very dis- 

 tinct. 



2. Twice as large, without the prominent groove. 

 Br. Zdol. t. 49. f. 36, Doxov. t. 96. Tellina. 



Shell about 4 lines long and Come what broader, white or bliiish, 

 often covered with a horn-colour skin, within hluish-white, with 

 tranfverfe black curves, one ot which is more distinct ; beak cen- 

 tral,, obtufe : primary-teeth, hardly any ; lateral-ones remote^ 

 laminate. 



236. C. amnicum. Oblique, suboval, convex, somewhat 

 pellucid, transversely grooved. 



Don. t. 64, /. 2. Linn. Trans, iii. t. 13. /. 37. 38. Tellina.. 



Shell t mailer than the last, horn-coiour, \vuh the beak placed near 

 one side : teeth one in one valve with 2 lateral ones, in the other 

 2, oblique, with a single lateral-one. 



331. C. iacuslre. Subrhombic, thin, pellucid, smooth, 

 flattish, with an acute projeciiug beak. 



C/umn. Conch, vi. t. 13/. 135. Tellina. 



Shell 3 lines long, 4 broad, greyish-brown with a white margin, 

 rather compressed : beak central, very prominent : teeth one in 

 each valve, one of which is cloven, with a lateral tooth each side, 

 and 2 minute lamina.' in one valve. 



40. MACTRA. 



238. M. solida. Sfrcng, opake, slightly triangular, with 

 a few concentric ridges and zones. 



Br. Zool. t. 51. /. 43. //. Donov. t. 61. Da Cost. t. 15. /. i. 



Shell an inch and a half long, an inch and 3 quarters broad, yel- 

 lowish-white with often yellow or bluish bands, glossy-white 

 within, equal at the sides: beak central. 



239. M. subtruncata. Strong, subtriangular, yellowish- 

 white, transversely striate, slightly truncate on both 

 sides. 



Donov. t. 126. Pr. Zool. t.^z.f. 42.. M. Stultorum. 



Shell 3 quarters of an inch long, an inch broad, a little produced 

 on one side, with f'ometimes a few ridges, yellowish-white within, 

 the sides near the beak much turned in : beak large, prominent. . 



240. M. Stultorum. Thin, semi pellucid, faintly striate, 

 slightly triangular, pale rufous with lighter radia- 

 tions, within pale purple. 



Donouan t. ic6. Br. Zool. t. \g.f. 30. Tellina. 



Shell an inch and a half long, an inch and 3 quarters broad, 

 nearly equal at the sides, often covered with a thin skin, irregu- 

 larly radiate with broad and narrow whitish lines: beak central, 

 prominent, often purplish. 



241. M. radiala. Thin, brittle, somewhat triangular, 

 produced at one end, whitish with regular pale testa- 

 ceous rays. 



Donovan Brit. Shells, v. tab. i6j. 



Shells, inches and a half long, nearly 3 wide, thin, brittle, dirty 

 white with a dull rufous tinge, and radiate with numerous equi- 

 distant narrow teftaceous rtys, finely striate tranfverfcly : beak 

 prominent, rather oblique. 



242. M. dsulbata. Oval, thin, brittle, pellucid, white, 



