■ LUCINA. 



TESTA ^equivalvi, insequilaterali, pleriimque siib- 

 depressa, lenticular! : dentibus, eardinalibus va- 

 riis, plerumque duobus, minutis, interdumsub- 

 niillis; lateralibus in altera valva utrinque uno 

 in altera duobus, interdum siibobsoletis: (dente 

 laterali antieo ad cardinem propius admoto.) 

 Ligamentum externum^ elongatum, marginibus 

 valvarum partim celatum. Impressiones mus- 

 culares duse, antica in faseiam, interdum pras- 

 longam, producta, postica subrotundata, minor. 

 Impressio rauseularis pallii sinu nuUo. 



The Linnean Genera Fenus and Tellina have each con- 

 tributed several species which appear to unite together 

 very naturally to form the Genus Lucina, which was first 

 established by Bruguiere, and has been adopted by 

 Lamarck and succeeding authors. In general form and 

 appearance the shells that compose this Genus approach 

 very nearly to Amphidesma, it is, however, easily known 

 from that Genus by its ligulate anterior muscular im- 

 pression; Amphidesma has, moreover, a very large sinus 

 in the muscular impression of the mantle, and the ten- 

 dinous portion of the ligament quite internal. It is 

 therefore, rather singular that Lamarck should have 

 placed several species of Amphidesmata among his Lucina. 

 From Cytherea the Lucinae may also be readily distin- 

 guished by the form of the anterior muscular impression, 

 which in that Genus is never ligulate, notwithstanding 

 which circumstance Lamarck has included some of the 



