&2 MOLLUSCA. 
close exactly, and have the lateral teeth obsolete. He de- 
scribes seven fossil species, and eleven recent ones, viz. 
mactra glabrata, (Encyclopédie Meth. tab. 257. fig. 3); ve- 
nus divaricata of Martini, (Conch. vi. p. 318. tab. 30. fig. 
317, 318,) under the title Crassatella contraria ; and the 
following new species, rostrata, Kingicola (from King’s Is- 
land!) donacina, sulcata, subradiata, erycinea, cycladea, 
and strata. 
The genus Erycina is composed entirely of fossil species. 
Lamark has assigned it the following character: “ Testa 
bivalvis, equivalvis, inequilatera, transversa. Dentes car- 
dinales bini, superne divergentes, cum foveola minima in- 
termedia: laterales compressi oblongi. Ligamentum fove- 
ola cardinali insertum.” From the situation of the ligament 
being inserted in the small space between the teeth, the pit 
or cavity is less than in any of the other genera. The mus- 
cular impressions are two in number. 
The transverse mactre, which gape, but are destitute of 
lateral teeth, such as the M. lutraria of Linnzeus, compose 
the genus Lutrarra of Lamark. The species already men- 
tioned, and the mya oblonga of Gmelin, or mactra hians of 
Montagu, occur on our coasts; the former in great abund- 
ance at the mouths of the European rivers. 
The genus Uneutrna, formed by Daudin, contains only 
one species, existing in the cabinet of Favanne. It is un- 
certain from what country it came. It is a regular longi- 
tudinal shell. The hinge is formed by one small tooth be- 
tween two oblique pits. The muscular impressions are two 
in number. It is figured in Deterville’s edition of Buffon. 
{ Hist. Nat. des Coquil. tom. xx. f. 2, 3.) 
Another genus established by the same author, and termed 
ERopona, is subtransverse, irregular, and gaping, the hinge, 
