WORMS. TESTACEA. 48. Mytilus. 163 



300. A. Squarnula. Suborbicular, thin, membranaceous,, 

 like the scale of a fish, entire, the flat valve trans- 

 versely wrinkled. 



Walker min. Shells./. 80. Adams microsc.J. 14./. 42. 



Shell about half an inch wide, whitish, within silvery or tinged 

 with green : beak prominent, pointed. 



SOI. A. aculeata. Suborbicular, thin, longitudinally stri- 

 ate, rough with small concave obtuse spine*. 



Montague Brit. Shells, p. 157. tab. 4. /. 5. 



Shell about 4 lines wide, dirty-white ; with interrupted longitu- 

 dinal striae : beak smooth, recurved. 



302. A. undulata. Suborbicular, pellucid, with fine irre- 

 gular undulate longitudinal smooth striae, crossing; 

 transverse curved ones. 



Donovan t. 45. Da Costa t. 11./. 4- Ostrea. 



Shell an inch or rather more wide, whitish, within perlaeeous 

 or greenish, mostly undulate on the margin, sometimes finely 

 striate transversely : beak small, pointed : aperture large, oval, 



303. A. cymbiforwis* Oblong,, coarse, slightly striate, 

 with the beak incurved, perf orated, on the flatter 

 valve. 



Linn,. Trans, viii.jj. 104. tab. 3./. 6. . , 



Shell 5 eighths of an inch long, 3 eighths broad,. whitish, very 

 tender. 



48. MYTILUS. Mussell. 



30t. M. edulis. Oblong-oval, nearly smooth, pointed and 

 slightly carinate at the beak, truncate and a little- 

 curved on one side. 



Br. Zool. t. 63./. 73. Donovan t. 128. Da Costa t. 15. /» 5. 



Shell about 3 inches long'half a one broad, blackish blue covered; 

 with a brown or yellowish skin, sometimes radiate with blue, 

 rounded at the bottom, within white in. the middle, blue about the 

 margin. 



305. M. incurvatus. Oblong-oval, nearly smooth,, much, 

 curved on one side under the hinge, beneath broad 

 and produced on the same side. 



Br. Zool. t. 64./. 74. Lister Conch, t. 357./. 19,5. 196. 



Shell resembling the last, except that it is less, the beak is more 

 truncate ; under which on one side it is very crooked and then 

 greatly dilated,, covered, with a thick rough skin, within 

 violet. 



306. M. ptllucidus. Oval, smooth, open, pellucid* whitish 

 or blackish radiate with deep blue or purple. 



Br. Zool. t. 63./. 75. Donovan tab. 81. 



Shell 2 inches long, one wide, a little gibbous on one side, co- 

 vered with a yellow skin, within bluejsh-white radiate with blue. 



307. ML. barbatus. Oval-oblong, roughish, thin, obtuse 

 at the beak, ferruginous-yellow^ obliquely clothed 

 with a thick beard on the lower-part., 



Br. Zool. t. 64./. 76. A.- Donovan t. 70. 



Shell about 2 inches long, one wide, short, ventricose, the-, 

 posterior side rising a little above the beak, within white, 

 clothed in an oblique manner with a thick beard on the lower 

 half: beak without crenulations within. Probably the young shell 

 of M, Modiolus, 



