39 



ANOMIA. 



GENERIC CHARACTER: Valves of the shell unequal, 

 irregular, opei -ciliated, adhering by the operculum; 

 smaller valve perforated, usually flat, having a hole close 

 to the beak ; the other valve larger, concave, entire. Oper- 

 culum small, elliptical, bony, connected with the internal 

 muscle, and fixed to solid bodies. 



Properly speaking, the perforated valve is to be regarded 

 as the lower one. And beside the muscular attachment of 

 the animal to the operculum (which is only the thickened 

 extremity of the tendon) the two valves are connected by an 

 inner cardinal ligament. 



* A. EPHIPP1UM. Tort. Lin. Pen. Brit. Zo., vol. 4, 

 pi. 62. Mont. Test. Brit., vol. 1, p. 155. Flem. Brit. An., 

 p. 395. Common. The largest specimens I have seen 

 were from Pinnae, in deep water. 



* A. CEPJE. Flem. Brit. An., p. 395. This well marked 

 species seems to have been overlooked or confounded with 

 others; from which it may be distinguished by its size, 

 which is from one and half to two inches in length, by its 

 undulated form, and by its colour ; being of a pale red, 

 and yellow, in broad, faint, irregular stripes: much re- 

 sembling an outer layer of the coats of an onion ; whence 

 the name. It is not uncommon, on rocks or the carapace 

 of Crustaceans. 



* A. SQUAMULA. Turt. Lin. Pen. Brit. Zo., vol. 4, 

 p, 109. Mont. Test. Brit., vol. 1, p. 156. Flem. Brit. 

 An., p. 324. Common, attached to every kind of sub- 

 stance. Montagu was inclined to suppose that this might 

 be the same as the two last named species in their early 

 state (vol. 2, p. 581), founding his remark chiefly on the 

 difficulty of distinguishing them, and indeed the remaining 

 kinds, when young. It must be admitted that at this 

 stage the distinction is not always easy ; but their appear- 

 ance is very different when fully grown. 



*A. UNDULATA. Mont. Test. Brit., vol. 1, p. 156, 

 pi. 4, fig. 6. Flem. Brit. An., p. 395 : — who supposses 

 Ostrea Striata of Montagu to be the same species. Com- 

 mon, though scarcely abuudant. 



* A, ACULEATA. Turt. Lin. Mont. Test. Brit., vol. 1, 

 p. 157, pi. 4, fi;;. 5. Attached to sea-weeds. 



* A. PUNCTATA. Flem. Brit. An., p. 395. Common. 



* A. CYLINDRICA. Flem. Brit. An., p. 395. Common. 

 A. INFLATA. Nobis. This, which I suppose to be un- 



described, is a minute species, the diameter of the disk 

 being about the tenth of an inch. The form is circular, 

 the valves smooth and regular; but it is especially cha- 

 racterized by the elevation of its centre ; which is almost 



