MOLLUSCOUS ANIMALS. 
125 
Monocjeros maculatum. 
Bucc. brevidentatum. Gray, Wood, Sup. t. 4 ,f. 10. 
Purp. cornigera. Blain. Mon. t. 9 . f. 10. 
Inhab. Pacific Ocean. 
QUOYIA. 
The foot is small, ovate, folded across and crumpled in front, side of the body quite simple. The pro- 
boscis short and ringed. The tentacles are slender, conical, far apart at the base ; the eyes are placed on short 
tubercles at their outer base. The mantle is simple, with a groove at the left angle, but (in the animal in 
spirits) without any appearance of any distinct canal, as is found in the other zoophagous Mollusca ; but in 
this character as in others it agrees with Planaxis. The operculum is half ovate, subspiral, of one and a half 
or two whorls; the nucleus is subapical. 
This shell only differs from the Planaxes by having a large groove on the hinder part of the inner lip, 
which is continued up the pillar, as is found distinctly formed in the young shell, and in the very small size of 
the anterior canal. The operculum is said to have a notch behind to fit this groove, but I do not find it in 
the specimen which I have examined, and I am inclined to think that it must have been an accident in the one 
in which it was described. 
The genus Planaxis has a somewhat similar, but not quite so spiral an operculum, and the opercula of 
these two genera are more spiral than those of any genera of zoophagous mollusca. This form of the oper- 
culum and the absence of the distinct canal to the front of the mantle, give some colour to Lamarck’s position 
of them amongst the Turbines ; and I might be induced to have continued them in this situation if there was not 
such a regular gradation of form and character between the Purpura and the Planaxis. 
TEREBRA. 
The tentacles of this genus are exceedingly minute, and placed on the upper edge of the inflexed trunk, 
and they have no eyes. In one species from St. Christopher which I have examined, there was no appearance 
of any tentacles, nor eyes ; in another, the tentacles were very small with'distinct eyes at their tip. The male 
organ is extremely long, filiform, as long as two whorls of the shell.- The foot is small, folded across when 
contracted. The head is rounded. The mantle has a very long slender filiform breathing canal. The oper- 
culum is horny, ovate, nearly as large as the mouth of the shell, with a rather thickened rib on its inner edge. 
In nearly all the species of this genus the inner lip is concave and absorbed ; in a few only it is thickened 
and elevated. 
Buccinum aciculatum and B.politum of Lamarck must be moved to this genus. 
EBURNA. 
The tentacles are triangular, rather short, separate at the base ; the eyes are small, near the outer base of 
the tentacles. The male organ is rather small ; foot longitudinally and transversely folded when contracted. 
The operculum is horny, acute in front, nearly as large as the mouth, concentrically striated, with the nucleus 
in front, and the inner ridge is thickened internally. (E. spirata). 
BULLIA. n.g. 
The animal of this genus is very peculiar for the very large size of its foot, which is much larger than 
the shell ; when contracted the foot is folded together, and is capable of being withdrawn into the cavity 
of the shell. They have no eyes ; arid the tentacles are long and subulate, and placed on the side of the head 
