CONCHOLOGY. 41 
A. longirostris. A. myalis. 
A. globulosa. A. rupicola. 
A.. Leana.* A. papyracea.* 
FAMILY V. 
Macrracea. Seven genera. 
1. Genus Lutraria. Pl. VI. 
Animal. Body oval, much compressed, or subcylindrical ; 
the mantle enclosed only in the half of its inferior side: foot 
small and projecting but little beyond the abdominal mass, tubes 
long, distinct or united. This genus is perfectly distinct from 
the Mactra, to which it formerly belonged, on account of its 
having no lateral teeth. It is called by De Blainville, Lutricola, 
from its being found very deep in mud or sand at the mouth of 
rivers. 
Shell. Oval or elongated, regular, equivalve, more or less 
inequilateral, sometimes but slightly gaping: edges always simple 
and trenchant ; summits feebly marked; hinge subsimilar, formed 
by two very small divergent cardinal teeth; two very distinct 
muscular impressions united by a palleal impression profoundly 
sineous to the rear. Inhabits the seas of Europe and America. 
Fourteen species. 
Lutraria solenoides. Lutraria elliptica. 
L. rugosa. L. papyracea. 
L. compressa. L. plicatella. 
L. piperata. L. crassiplica. 
L. tellinoides. L. complanata. 
L. candida, 
L. lineata.* L. Nuttallii.* 
L. caniculata.* 
2. Genus Macitra. PI. VI. 
Animal. Body oval and pretty thick; edges of the mantle 
4* 
