384 Scientific Proceedings of the 
for the British shell, he has given as synonyms the names of three distinct 
species. In the “ Catalogue of the Animals and Plants of Massachusetts,” 
in Prof. Hitchcock’s Report of his Survey of Massachusetts, it is set down 
as Anatina convera, Wood. In Dr. Storer’s excellent translation of Kie- 
ner’s “Iconographie,” it is regarded as identical with Th. corbuloides, 
Deshayes. From this it differs, however, in several important particulars, 
such as its less elongated form, less truncated extremity, smooth surface, 
and above all in the palleal impression forming posteriorly a deep and al- 
most acute angle instead of the semicircular one of Th. corbuloides. The 
only locality where this shell has been found alive is believed to be Chel- 
sea Beach. 
Mr. C. conjectured that Mya (Ligula) distorta, Montagu, referred by 
Kiener to Th. corbuloides, would prove to belong among the perforating 
Corbule ; and to these also he was disposed to refer Anatina truncat1, 
Turton. Both of them have similar habits of burrowing in the limestone 
of the British coast. 
July 18, 1838.—G. B. Emerson, Esq., President, in the chair. 
Mr. Cournovy, continued his paper on the Osteodesmacea, and made 
remarks upon the following species. 
PerreLoma TRAPEzowES, Deshayes. Periploma inequivalvis, Schum. ; 
Anatina trapezoida, Lam.; Osteodesma trapezoidalis, Blainville. 
Blainville was led into the error of placing this shell in the genus Os- 
teodesma from supposing it to be identical with Lamarck’s Anatina my- 
alis, But he has committed another serious error in his generic descrip- 
tion, which has been adopted by Rang in his ‘‘ Manuel des Mollusques.” 
He says the shell is “ inéquivalve, la valve gauche plus bombée que la 
droite,” whereas the right valve is more convex than the left. Perhaps 
they were misled by the peculiar position of the ligament, which is re- 
markable for being placed anteriorly instead of posteriorly, as in most 
other shells; a fact not noted in any description. In the very perfect spe- 
cimen under observation the ossiculum is nearly a complete semicircle. 
Deshayes speaks of it as triangular. 
OsreopesmA nyattna, Couthouy. Mya hyalina, Conrad. : 
The genus Osteodesma, Deshayes, will doubtless prevail over Lyonsia, 
Turton, and Magdala, Leach, MSS., all of which are founded on Mya 
Norvegica, Chemnitz, the Amphidesma corbuloides of Lamarck. The 
name is expressive of the distinguishing feature of the shell. Blainville 
and Rang were led into the error of supposing Periploma and Osteodesma 
to be identical ; and Deshayes, though he notices the mistake and refers 
to his article on Osteodesma in the Encyc. Method. for its actual charac- 
ters, yet by a singular oversight that article is entirely omitted. mig 
quently, it is to be found only in his recent edition of Lamarck. In Se 
“Catalogue of Animals and Plants of Massachusetts, 1834," it 1s not 
