226 DENTALIAD A. 
1849, it appears that the mimute species of the genus Cecum, 
from their configuration, have generally been located with the 
Dentalia, though it will be seen that there is little concordance 
between the animals of the two genera. I believe, with the 
exception of M. Deshayes’ monograph, that nothing has been 
done to elucidate this curious molluscum ; and as I think that 
eminent malacologist has mistaken the uses of some of its 
organs, I am induced, by the facility of obtaining live speci- 
mens of the Dentalium Tarentinum, to review and augment 
what is at present known of it. The animal exhibits a series 
of characters of the highest imterest, in its anatomy and 
functional developments, some of which are so anomalous, that 
it must be considered one of the most singular of the testa- 
ceous mollusca. 
DENTALIUM, Linneeus. 
D. Tarentinum, Lamarck. 
D. Tarentinum, Brit. Moll. ii. p. 451, pl. 57. f. 12. 
Animal yellowish-white, conically elongated, mantle circu- 
lar, anteriorly thick and fleshy, edge dentated, posteriorly of 
the thinnest texture; the penultimate and antepenultimate 
portions of its margin are bounded by two intense white mus- 
cular elastic cordons; the united action of these has the 
power of completely opening and closing the anterior aper- 
ture; when at rest, the animal, including the foot, is entirely 
enclosed by the tougher part of the mantle which supplies the 
place of an operculum. 
The foot is a very long and singular organ, placed m the 
centre of the anterior end of the body, and from its position is 
applicable for use in every direction ; it is divided into three 
parts: the anterior one is a poimted cone acting in some 
measure as a tentaculum, and lies in the middle portion, which 
consists of two lateral, smuated, symmetrical flaps or tena- 
cula, that are usually protruded simultaneously with the 
terminal portion, and are the parts subservient to the animal’s 
very confined locomotion, by using the lateral appendages as 
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