79 



CHAPTER XVIII. 



OF THE ANOMIA. GENUS XV. 



ANOMIA. 



"Animal a strap-shaped body, emarginate and ciliate, with fringes 6x1 to 

 the upper valve ; arms two, linear, longer than the body, near together 

 extending, alternate on the valve, both sides fringed, with fringes fixt 

 to both valves. Shell with unequal valves, one of the valves flattish, the 

 other more gibbous at the base, one of them often perforated at the base ; 

 hinge without teeth, with a linear prominent cicatrix and a lateral tooth 

 within, but in the flat valve on the very margin. Two bony rays for the 

 base of the animal." — Linn. 



The different species which compose this genus of shells vary 

 considerably in their form ; most of them are thin and brittle, 

 semi-transparent, of a pearly texture ; in general they will be 

 most readily known by having one of the valves perforated 

 (J. 47. a) : several species have the lower valve flat, and the upper 

 convex, the flat valve having a large hole close to the hinge, 

 through which a strong muscle or ligament passes : one end 

 of this muscle is attached to the upper or convex valve, and, 

 passing through the perforation in the flat valve, the other end 

 is attached to a small operculum, which operculum is generally 

 fixed to some other substance, as A. Ephippiion, which is often 

 found attached to the common Oyster. If the muscular im- 

 pression on the convex valve in this species is examined, it will 

 be found to consist of three parts, as if there were three liga- 



