- 
oa 
E 
132 Couthouy's Monograph on 
mentioning the existence of an ossiculum attached to the 
ligament, I have inserted the word * sometimes," be- 
cause it does not appear to be a constant character. 
Although M. Deshayes having seen it in one species, 
presumes it to exist in all, yet, as it is not mentioned . 
in any of those described by him in the Encyc. Me- 
thodique, nor in any of the descriptions of those found on 
the British coast ; nor by M. Kiener, in his Iconography, 
and is not met with in 'T. Conrádi, Nobis, of our own 
shores ; — it is evident that it it is not to be admitted as a 
generic character without this qualification. 
M. Deshayes, in his preliminary observations on 
Thracia, Encycl. Method. Vers, vol. HI., states, that he 
has observed the existence of an ossiculum in one species 
at least, and concludes from analogy that it is common 
to all, and this assertion is repeated in his recent edition of 
Lamarck, VI. p. 82; but strangely enough he has neg- 
lected, in either work, to designate in any way the spe- 
cies referred to. True, in the article Anatina of the 
Encyclopédie, he speaks of having witnessed an ossi- 
culum in several of Lamarck's genus of that name, and 
among others, instances A. mydlis, which, in his edition 
of Lamarck, published three years later, he considers 
the type of Thracia. In his notes upon Anatina, how- 
ever, in that work, VI. p. 77, he contradicts this state- 
ment by remarking, “enfin ?_Anatina myális, Lam., 
It might be Mes that this settled the question, but 
on turning to his note on this same species, page 82, of 
the same work, we find him adopting for it the descrip- 
tion given by M. de Blainville, of the animal erro- 
