the Family Osteodesmacea. 131 
* 
British writers with another species, Mya declivis, 
Donovan, [Anatina convéza, Turton and Brown]. A 
more serious error, and one far more injurious in its re- 
sults, as it confounds genera as well as species, is that 
committed by M. de Blainville, in consequence of im- 
agining a shell before him to be Lamarck’s ANATINA 
— and suppressing be: species as a "Thracia, on 
nonymous with arcs S o 
ede page 659 € s odd Nouvelles additions et 
corrections.’ 
That the shell here characterized by M. de Blain- 
ville, was not in truth A. myàlis, but some other species, 
there can hardly exist a doubt, as it will presently be 
attempted to show. 
M. Rang, in his * Manuel des Mollusques,” gemisi 
284, has adopted the error of M. de Blainville, in 
garding as identical, the two genera just referred to; but 
expresses a conviction that it was the animal of some 
other species than A. myàlis, which served for the obser- 
vations of the latter, as he- had himself examined the 
animal of that shell, and found. it to differ materially 
from the description given’ uie * Manuel de Mala- 
cologie." 
M. Deshayes, in his recent tm of Lamarck, while 
he points out one mistake > by M. de Blainville, 
in confounding Osteodesma eriploma, perpetuates 
another, by quoting the characteristics of the species ex- 
amined by that naturalist, as really pertaining to A. 
mydlis. The generic characters of Thracia, here given, 
are taken from Deshayes and Blainville. In that part 
$ 
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