110 
This species^ like the galea, is often found coated over with the 
cortical envelope of the Gorgonia, and the animal destroyed, pro- 
bably by its encroachment. 
CoRONULA DENTULATA. — Shell depressed-conicj base oval; 
height equal to about one-third of the base ; valves and interstices 
smooth, the anterior valve largest, and the posterior one smallest ; 
operculum transversely striated, the posterior pair of valves with a 
submarginal impressed line, from which to the edge are drawn 
three or four other impressed lines. 
Found on the clypeus of Limulus Polypliemm. Collection of 
the Academy and Philadelphia Museum. 
The posterior margins of the posterior valves of the operculum, 
are divided by the impressed lines into three or four broad, flat, 
dentiform divisions, which, however, but simply crenate the edge. 
[J. A. N. S. Vol. ii. p. 378, et seqq. Dec. 1822.] 
Lymneus humilis. — Shell ovate-conic, thin, translucent, with 
slight wrinkles ; volutions nearly six, convex, terminal one very 
minute ; suture well indented ; aperture about equal in length to 
the spire ; labium with an obvious plate of calcareous deposit ; a 
distinct and rather open umbilical aperture ; color pale reddish- 
white or yellowish-white. 
Total length seven- twentieths. Inhabits South Carolina. 
Of a dozen specimens sent me by Mr. Elliott, none exceeded 
the limit here assigned to the species. It differs much from any 
other species I have seen ; a variety of it, sometimes quite black, 
was found by Dr. M’Euen at Oswego, on the Susquehanna. 
It may be useful here to remark that, in consequence of a typo- 
graphical error in the first part of the second volume of this work, 
the species above described may be confounded with the desidiosus. 
The length of that shell is erroneously stated to be seven-twentieths 
of an inch, instead of seven-tenths, its true length. 
Paludina grana. — Shell conic-ovate ; whorls not perceptibly 
wrinkled, convex ; suture deeply impressed ; aperture orbicular, 
hardly angulated above ; labium with the superior edge appressed 
to the surface of the penultimate volution ; umbilicus rather 
profound. 
Length less than one-tenth of an inch. Inhabits Pennsylvania. 
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