CONCHIFERA. 725 



A. Monomyaria. Muscular impression single, subcentral. In- 

 ternal ligament received in a cardinal pit, partially visible on the 

 outside in some, mostly included. 



The single adductor muscle here corresponds to the posterior adductor of 

 those conchifers that have two of them. All the single-muscled conchifers 

 live in the sea. 



Family II. Ostracea. Mantle open. Foot none or a small 

 rudiment of foot, not byssiferous. Shell irregular, lamellose. 



Anomia BRUG. (Species of genus Anomia L.). Shell inequi- 

 valve, thin, one valve flat, perforate or emarginate towards the 

 point, the other larger, more gibbous at the base. Animal (Echion 

 POLI) with foot small, tentacles at mouth none, margin of mantle 

 cirriferous, adhering to marine bodies by a muscular cord perforat- 

 ing the shell and inserted into the calcareous cover. 



The name Anomia was first employed by F. COLUMNA (DePurpura, 

 Komse, 1616) and given to those conchifera which are now named 

 Terebratula. LINNAEUS united with these some very different con- 

 chifers also under the name of Anomia, although what he says in the 

 description of the characters of this animal (Sys. Nat., ed.12, i. p. 1 150) 

 applies to Terebratula alone. JSRUGUiURE^JZncycl.meth., Vers. I. p. 70) 

 was the first who gave the name of Anomia to the present genus 

 and placed it in the neighbourhood of the oysters. From these, 

 however, it differs by many essential characters, so that DESHAYES 

 has placed it even in a separate family. There are properly three 

 muscles of which the impressions are seen on the convex valve, but 

 on the flat valve only a singular muscular impression appears. This 

 impression is that of the muscle which corresponds with the central 

 depressor of the oyster ; the two other muscles, which are attached 

 to the convex valve, go through the aperture of the flat valve and 

 fix themselves to the calcareous cover, which is often very hard, 

 whence it is named by several writers a little bone (ossiculum). By 

 that cover the shell is attached to other conchifera or to rocks. See 

 DESHAYES Diet. Univ. d'Hist. Nat. i. 1841, pp.557 559, and the 

 figures of the three muscles in POLI Testae, utr. Sicil. Tab. 30, fig. 

 1, and in Cuv. R. Ani. } ed. ill, Moll. PL 79. 



Sp. Anomia Epkippium L., LISTER Conch. -204, CHEMN. Tab. 76, figs. 692, 

 693, BLAINV. Malacol. PI. 59, fig. 31, Cuv. R. Ani., ed. ill., Moll. PL 79; 

 Mediterranean, Atlantic ; this species is very flat, the shell is mostly of a 

 whitish colour; Anom. cepa L., POLI Tab. 30, figs, i, 8, is more convex, 



