80 MOLLUSCA. 



even with his own definition. Hence several important im- 

 provements have taken place in the distribution of the species. 



The first change in the genus of any consequence con- 

 sisted in the separation of the fluviatile from the marine 

 species. This was accomplished by Scopoli, (Introd. ad 

 Hist. Nat. 397), who bestowed on them the generic name 

 of SpJuerium. Bruguiere afterwards wantonly changed the 

 name to CYCLAS, and this change has been embraced by 

 Lamark and other naturalists* 



Another new genus of fluviatile shells, allied to the pre- 

 ceding, has been formed by Bruguiere and Lamark for the 

 reception of one species. The genus is termed GALATKEA, 

 and the species G. radiata. There are two approaching 

 hinge-teeth in the right valve, with a cavity in front, and 

 two distant hinge-teeth in the left, with an intermediate 

 large grooved callosity. The lateral teeth are of consider- 

 able size. The ligament is external, and the muscular im- 

 pressions are two in number, and lateral. 



The Tellina incequivalvis presents characters which read- 

 ily distinguish it from the other species with which Linnaeus 

 placed it. The shell is inequivalve and inequilateral ; the 

 ligament is internal, and the lateral laminae are wanting. 

 Besides, the animal differs from the other inhabitants of the 

 tellinae, and is nearly related to the solens. Hence Brugu- 

 iere formed a new genus for its reception, which he termed 

 PANDORA. 



There are several species of the genus telling and Venus, 

 which Bruguiere and Lamark have formed into a separate 

 genus called LUCINA, which is thus characterised : " Testa 

 bivalvis. aequivalvis, orbiculata, vel ovato transversa ; nati- 

 bus arcuatis, postice versis. Cardo dentibus cardinalibus 

 1 . s. 2. variabilibus ; lateralibus 1 . s. 2. remotis, interdum 



