108 Description of Eight new Species of Shells. 
Shell transverse, obovate, smooth, polished, greenish, diapha- 
nous, marked with purple lines; valves thin; beaks ening 
prominent, sub-acute. a 
Length ‘08. Breadth -15. Diam. -05 of an inch. er 
Var. «. Minore, compressiore, castaneo-brunnea, sine line One 
purpureis. ” hela 
Smaller, more compressed, chestnut-brown, without purple lines, as 
Hab. Delaware Bay. Cabinet of I. Lea. esc 
Remarks.—This species varies very much, both in form id” a * 
color. The var. « may perhaps prove a species. "The markings, — sigh’ 
as in the preceding species, are frequently zigzag. There are 
transverse lines of growth, only visible with a powerful micro- 
scope. In form it somewhat resembles the Modiola tulipa. It 
might be confounded with the very young of Mytilis edulis, but 
the difference in color and shape, as well as in the position of the 
beaks, will distinguish it on a very slight examination. 
Genus Crepipu.s.— Lamarck, 
C. acuta. PI. 1, fig. rea 
C. testa ovata, valde convexa, sub-tenui, levi, externé fusca, 
intus tenebroso-castanea ; epidermide luteo-fusea : apice acuto, 
recto; cyatho sub- ‘stialivtlad, albido, diaphano, sub-convexo, 
vix sede trienti teste longitudinis ; apertura elliptica. 
Shell ovate, very convex, somewhat thin, smooth, externally 
brown, internally dark chestnut ; epidertiie yellowish brown; 
apex acute, straight ; cyathus sub- tht alad whitish, diaphanous, 
somewhat convex, ‘geareely equal to a third the length of — 
shell; mouth elliptical. 
Length ‘17. Breadth -1. Height 05. Length of cyathus 
‘05 of an inch. 
Hab. Delaware Bay. Cabinet of I. Lea. 
_ Remarks.—This little species of Crepidula belongs to the Cre- | 
pipatella, Lesson, a sub-genus of Calyptrea. The color intet- 
nally varies from a chestnut brown to a horn color with browa 
marks. The eyathus or diaphragm, in common with our othet 
Species, is convex, the convexity usually ending at a regular line, 
about one fifth from one side, beyond which it is flat ; it also ge®- 
erally comes a little further down on one side than on the other. 
It is usually very regular in its form. It bears a slight resem- 
blance to the Crepidula glauea, but that shell is flatter when 
young than when old; esha shia sera less width, 
and want of transverse lines, will immediate hit. It 
