Ae SHELLS OF NEW ENGLAND. 
—Corall. St. George’s Bank. This is perhaps M. 
Saba, O. Fabr. 
M. corrucatus, St. Modiola discors, Gould. (non Angl.) 
— Corall. Eastport, in 40 f. sandy mud, (W. 8.) to 
Cape Cod. 
M. piscors, Lin. Modiola discrepans, Lam. Crenella 
discors, ¥.et H.— Lamin. Eastport, from low water 
to 20 f. gravel, (W. 8.) to Cape Cod. 
M. Levieatus, St. MM. discors,O. Fabr. Mod. levigata, 
Gray. Mod. discrepans, Gould, 129, f. 83.— Corall. 
St. George’s Bank. This species differs from M. 
discors, in being larger, more ventricose, and narrower 
posteriorly. 
M. piscrepans, Montagu. (in part.) Modiola nigra, Gray. 
Mod. nexa, Gould. (young.) Crenella nigra, F. et H. 
—Lamin. Eastport, 5 f. and Grand Manan, 40 f. 
(W. 8.) Provincetown Harb. (Tott.) Stonington, 
(Lins.) It prefers shelly bottoms. The Crenelle of 
the European shores have a habit of boring into the 
tests of Ascidie, (see British Mollusca, ii. 95,) which 
the same species on our coast do not have. They 
are sometimes found imbedded in sponges and mas- 
sive algee, but in this case the matrix seems to have 
grown around them. 
M. piicatuLus, Desh. Modiola plicatula, Lam. Gould, 
125, f. 81. — Litt. From New Hampshire southward. 
M. moprouus, L.— Whole Coast. Litt. to Corall. 
M. eputis, L.— Whole coast. Littoral. 
The determinations of some of the above species by 
Middendorff (Mal. Ross. ii.) seem at variance with 
