104 .AMERICAN MARINE CONCHOLOGY. 



Doubtful Speciea. 



0. semicylindrica, Saj'. This appears to be an immature shell 

 and is not identified. It is said to inhabit the coast of Georgia 

 and Florida, imbedded in sponges. 



Genus ANOMIA, Linnfeus. 

 Syst. Nat., edit. xii. 1150. 17G7. 



Animal with the mantle open, its margins with a short double 

 fringe ; lips membranous, elongated ; palpi fixed, striated on both 

 sides ; gills two on each side, united posteriorly, the outer laminae 

 incomplete and free; foot small, cylindrical, subsidiary to a. 

 lamellar and more or less calcified byssal plug, attached to the 

 nppcr valve b^^ three muscles ; adductor muscle behind the byssal 

 muscles, small, composed of two elements ; sexes distinct ; ovary 

 extending into the substance of the lower mantle-lobe. 



There are about twenty species ; distribution principally in tem- 

 perate seas, from low water to 100 fathoms. 



1. A. GLABRA, Terrill. Fig. 534. 



Am. Jouni. Sci., 288. April, 1872. 

 A. ep7ii2)2num, Gould. Invert. Mass., edit. i. 1841. 

 A. clectrica, Gould. Invert., edit. ii. 205. 1870. 



Shell orbicular, or distorted ; surface scaly, lamellar, and easil}- 



impressed by contact with other shells, etc.; npper valve very 



convex, with a small beak ; lower valve smaller, flat, or concave, 



with a circular byssal hole, which is united to the margin by a 



greater or less fissure. Polished, and varying in color from black 



through red, yellow, and ash to white ; the same colors internally, 



except that the muscular impression is opaque white. 



Diameter usually about 1 inch. 



C((j)e Cod, Mass. to Florida. 



This is our common Ajiomia, generall}' known as A. ephippmm^ 



but it appears to be distinct from the European shell bearing that 



name. 



2. A. ACULEATA, Gmelin. Figs. 535, 53G. 



Syst. Nat., 3346. 1790. 

 Shell small, rounded ; upper valve with fine, prickh' scales ar- 

 ranged in radiating lines ; lower valve smooth ; yellowish or 

 whitish. 



Diameter about half an inch. 



Eastport, Maine, northicards. 



