132 MOLLUSCA. 
of a fleshy pedicle, which attaches the shell to rocks, madre- 
pores, other shells, &c. Internally, a small bony piece of 
frame-work is observed, sometimes sufficiently complex, com- 
posed of two branches that articulate with the imperforated 
valve, and that support two arms, edged all round with a long 
close fringe, between which, on the side next to the large 
valve, is a third simply membranous, and much longer ap- 
pendage, usually spirally convoluted, and edged like the arms 
with a fine and close fringe. The mouth is a small vertical 
fissure between these three large appendages. ‘The principal 
part of the body, situated near the hinge, contains the nume- 
rous muscles, which reach from one valve to the other, and 
between them are the viscera, which occupy but little space. 
The ovaries appear to be two ramified productions adhering to 
the parietes of each valve. I have not yet been able to ascer- 
tain exactly the position of the gills. 
Numberless terebratule are found fossil or petrified in cer- 
tain secondary strata of ancient formations. The living spe- 
cies are less numerous. (Anomia scobinata, &c.) 
The shell of some is broader transversely, or longer in a 
direction perpendicular to the hinge, with an entire or emar- 
ginated contour, divided into two or several lobes; some of 
them are even triangular. ‘The surface is either smooth, fur- 
rowed in radii, or veined; they are thick, and thin, and even 
diaphanous. In several of them, in lieu of the hole in the 
summit of the thin valve, there is a notch, and this notch is 
sometimes partly formed by two accessory pieces, &c. It is 
probable that when better known their animals will present 
generic differences. Already, in the 
SPIRIFER, Sowerb., 
Two large cones have been recognized, formed of a spiral 
thread, which appear to have supported the animal. In 
OE 
