90 MOLLUSCA. 
the perne, which he styles CrenaruLa. The hinge in this 
genus presents only a row of pits for the ligament, which 
makes it appear crenulated. The intermediate spaces are 
not formed into teeth, neither is there any callosity, or 
opening for the byssus. He has figured two new species, 
which he terms avicularis and mytiloides, and a third is the 
ostrea picta of Gmelin, (Chemn. Conch. vii. p. 243. tab. 38. 
f. 575.) 
Nearly related to the pectens is the genus Lima of Bru- 
zuiére. The species differ, however, in the ligament being 
in a great measure on the outside. They are all of a white 
colour. The ostrea lima is considered as the type of the 
genus. 
The genus Pepum of Brugui¢re differs from the preced- 
ing in the ligament being external, and attached to a long 
straight fissure. The ostrea spondiloidea of Chemn. (Conch. 
viii. t. 72. fig. 669, 670,) is considered as the type of the 
genus. 
To this family we must add two genera, possessed of very 
singular characters. They have neither hinge nor ligament. 
The first, instituted by the celebrated botanist, Commer- 
son, is termed Acarpo. The valves are depressed and — 
nearly equal, and held together by the adductor muscle. 
The species at present known come from the eastern coast 
of Africa. The second is termed radiolites, and was insti- 
tuted by Lamark. It differs from the former in the form 
of the valves, the inferior being turbinated, and the supe- 
rior convex or conical. The species occur only in a -fossil 
state, and have been long known to geognosts under the 
title ostracites. 
15. Anomra. In the Linnean system, this genus is equ- 
ally faulty as the last. It contains many species, which 
