ACROLOXUS. 231 
Genus ACROLOXUS, Beck. 
A. Eastern Species. 
1. ACROLOXUS OVALIS, Morse. 
Plate 2, figs. 5, 6. 
Shell very small, depressed, irregularly 
ovate, apex nearly central, round, smooth and 
blunt, slightly inclined to the left; slopes 
irregular, caused by different periods of repose 
and growth; posterior slope in most speci- 
mens straight, anterior slope convex, lateral 
slopes steep; shell widening anteriorly; lines 
of accretion extremely fine, visible within but 
requiring a magnifier to discern them without, 
being greatly obscured by fine grains of sand 
agglutinated to the surface. Periostraca pale 
yellow; the surface, when magnified, exhibits 
about forty-five delicate ribs, which radiate 
from the apex to the periphery of the shell. 
Length 3, width 2:5, alt. 1:5 mill. 
Androscoggin River, Maine. 
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