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 Spherium. Bruguiére afterwards wantonly changed the 
name to Cycias, 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 Bruguiére and Lamark for the 
reception of one species. The genus is termed GALATHEA, 
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 inequivalvis presents characters which read- 
ily distinguish it from the other species with which Linnzeus 
placed it. The shell is inequivalve and inequilateral ; the 
ligament is internal, and the lateral laminz are wanting. 
Besides, the animal differs from the other inhabitants of the 
tellinze, 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 tellina and Venus, 
which Bruguiére and Lamark have formed into a separate 
genus called Lucia, which is thus characterised :—“ Testa 
bivalvis, zequivalvis, orbiculata, vel ovato transversa ; nati- 
bus arcuatis, postice versis. Cardo dentibus cardinalibus 
1. s. 2. variabilibus ; lateralibus 1. s. 2. remotis, interdum 
