92 MOLLUSCA. 
To Lamark we are also indebted for having formed the 
genus CaLcEouLa from the anomia sandalum of Linneus. 
The largest valve is sandal-shaped, and has at the hinge two 
or three small teeth. The other valve is small, flat, semi- 
orbicular, and resembles an operculum. It is frequent ina 
fossil state in Germany. 
Mr. Sowerby, in his valuable work on British Mineral - 
Conchology, has made us acquainted with several new 
genera of fossil shells, which, by the older naturalists, would 
have been inserted in the genus Anomia. The genus PEN- 
TAMERUs is an equal-sided inequivalve bivalve, with one 
valve, divided by a longitudinal internal septum into two 
parts, the other by two septa into three parts or valves. Beaks 
incurved, imperforate. He has figured three species of this 
curious genus. 
The genus PLaciostoma of Sowerby, is represented by 
the Pecteuites Plagiostomus of Luid, (tab. 10, f 639,) and 
is thus defined: “ An oblique eared bivalve, hinge destitute 
of teeth or internal pit. Line of the hinge straight in one 
valve, in the other deeply cut by an angular sinus.” He 
gives figures of two species in his first volume, the gzgan- 
tea and the spenosa; and many others have been subse- 
quently detected. 
The genus Drancuora is nearly related to the preced- 
ing, but in this the shell is fixed, and the attached valve has 
an opening in place of a beak. The other valve is beaked 
and eared. 
The anomia spznosa of Linneeus probably belongs to Mr. 
Sowerby’s genus Propuctus, which he thus defines: “ An 
equilateral unequal-valved bivalve, with a reflexed, more or 
less cylindrical margin ; hinge transverse, linear ; beak im- 
perforate ; one valve convex, the other flat or concave ex- 
