genus from Mytilus (muscle), wink which it had been con- 
founded by all preceding writerszs 
All the Modioles inhabit the sesh their shells are readily 
distinguished from those of true mitséles. by the position of 
the beak, which is in that genus terminal, in this lateral. 
The species, without any violation of nature, may be 
arranged into the following sections : 
* Hinge without teeth. 
a. Shell smooth; hinder side wing-shaped. 
b. Shell longitudinally and obliquely striated with raised ribs. 
c. Shell with the two extremities ribbed; hinder side rounded. 
** Hinge with teeth. 
a. Shell smooth; hinder side rounded. 
b. Shell longitudina/ly or obliquely striated; hinder margin 
wing-shaped. 
© ai 
The shells of the Modiole of this section, when young, 
have their epidermis elevated and beard-shaped. 
Se. 1. MODIOLA AMERICANA. 
‘Tras. LXXH. Freel. 
M. testa fusca (sub epidermide oblique radiata) ; latere pos- 
tico ala subangulata; latere antico subsinuato. 
Habitat in oceano Americano, 
AMERICAN MODIOLE. 
Shell fuscous (beneath the epidermis obliquely rayed) ; hin- 
der side with the wing slightly amped 3 ; anterior side 
slightly sinuated, } 
The specimen from which our figure i is taken, was re- 
ceived from Bermuda, and is preserved in the British Mu- 
seum. It is not an uncommon shell in the American seas: 
