464 PELORIDA. 
Authors state that Natica has affinity with Sigaretus, an 
exotic genus of which there is no true British species. We 
cannot concur in this view until the anatomy of the latter is 
more fully examined: if it be found to have the retractile pro- 
boscis, it will be in the same category as Natica, and must be 
withdrawn from the Haliotide. 
N. moniirera, Lamarck. 
N. monilifera, Brit. Moll. in. p. 326, pl. 100. f.1; (animal) pl. P.P. 
f. 6, as N. canrena. 
N. glaucina, Auct. 
Animal inhabiting a spiral, globosely conical, smooth shell of 
6-8 tumid volutions. The mantle, neck and body are of the 
palest or ightest mouse-colour ; the mantle is thin, rather lax, 
but does not extend beyond the shell. Lamarck’s commentator, 
M. Deshayes, says, “Le manteau se développe particuliére- 
ment sur les parties antérieures de la coquille:” this is quite 
incorrect; he has mistaken the upper skin of the anterior 
portion of the foot, which some call the mentum, for the 
mantle. There is no distinct head; the only vestige of one 
is a compressed arcuated veil which is fixed by the centre of 
its membrane on the anterior part of the fleshy tunic of the 
proboscidal sheath, and on each side by a small white muscle 
to the base of the groove formed by the neck and skin of the 
foot, at the centre of which, and under the veil between it 
and the inside of the front skin of the foot, the yellowish- 
white proboscis and the end of its immer cylinder may be seen 
retracted; the head-veil is shallow, simuous, or lunated, 
breaking at the right and left sides, very far apart, into two 
moderately long, flat, triangular, pomted tentacula, red-brown 
on the upper and outside half, and white on the lower and 
inside portion, forming at the extreme angles small subcircular 
auricles. The eyes in this species are so excessively minute 
as scarcely to be detected; however, if they really exist, we 
know their precise position by those of N. nitida, m which 
they are very visible and immersed in the skin at the centre of 
the anterior base of the tentacula, on the white concealed 
portion, but being always covered, they appear to be of little 
