On the Mollusea of Long Island. 165 



the animal, were thrown up on ]l*«rapeague Pt. after an easterly 

 gale. (See Coch. Leanum.) 



95. Saxicava distorta Say. A few specimens are occasion- 

 ally thrown up on the beacli, attached to the roots of fuci. 



96. Teredo {jorohahly dilatata Stimpson). Rare ; in piles 

 from a pier. 



Tunicata. 



Both the simple and compound Ascidians are very numerous. 

 I have prepared descriptions of a large number of species, most 

 of which, so far as I can ascertain, are undescribed, at least 

 from the American side of the Atlantic ; but as I have not yet 

 been able to fully satisfy myself as to those which are identical 

 with described species, I think it safer, for the present, to defer 

 describing or naming those which I suppose to be new. The 

 genera noticed are Ascidium, Molgula, Cynthia, Botrjllus, 

 Botrylloides ? Didemnium, Aplydium, and Amoroecium or its 

 subgenus Parascidium ; and the number of species is at least 

 eighteen or nineteen, and I am disposed to think, much greater. 



(Note.) The remarks as to size, depth at which dredged, &c., 

 annexed to each species in this paper, refer, unless otherwise 

 stated, only to the species as occurring within the strict limits 

 of the two bays named. Remarks as to size, &c., in the neigh- 

 boring waters, are, in a number of instances, added. 



The extreme depth of water in Peconic Bay is ten or eleven 

 fathoms. Gardiner's Bay is a good, deal shallower, there being 

 few places where more than five fathoms can be found. 



For determinations of most of the species about which I have 

 felt any doubt, as well as for much other assistance, I am in- 

 debted to Mr. "Wm. Cooper of Hoboken, and to Mr. Stimpson 

 of Washington. 



I have adopted, without exception, the names of Mr. Stimp- 



son's " Synonymy of the Shells of New England," not having 



had sufficient opportunity to acquaint myself with the more 



recent changes in nomenclature. 



I 



