MURICIDA. 119 
ture oblong, produced anteriorly into a wide, subrecurved canal. 
Operculum unknown. 
This, like the preceding genus, has only one properly authen- 
ticated species ; and that is unquestionably very closely related 
to Leptoconchus. The operculum is of the normal purpuroid 
type, but like the shell, very thin, translucent and yellowish 
white. 
Maaiuus, Montfort. 
Syn.—Campulotus, Guett. (part). Tubulites, Davilla. Lep- 
toconchus, Ruppell. 
Distr.—5 sp. Coral Reefs, Mauritius, Red Sea. IM. antiquus, 
Lam. (xlv, 52, 53). 
Shell when young, spiral, thin; when adult, white, solid, 
tubular, spiral for three or four whorls, the last prolonged into 
an irregular straight or flexuous tube, solid posteriorly, and with 
a siphonal keel on the left side. Operculum ovate. nucleus sub- 
lateral. 
In the “ Genera of Recent Mollusca,” the authors, following 
Ruppell, distinguish the species of Leptoconchus from the single 
species of Magilus. They thus describe the animal of the 
former : 
The mantle-margin is greatly thickened and fleshy ; the tenta- 
cles are small, broad and united at their bases; the eyes are 
small and black, on the outer side of the tentacles, near their 
tips; the foot is small, short, obtuse and rounded behind, with 
a thin, expanded, disk-like lobe in front, and the siphon is obso- 
lete. The genus differs from Campulotus (Magilus) not only in 
the absence of the operculum, but in the shell never forming a 
long tubular projection of the mouth as in that genus. It com- 
prises but few species, which take up their abode in corals and 
madrepores. 
Deshayes, in his ‘‘Conchology of the Island of Bourbon,” 
1862, describes a number of species of Leptoconchus as well as 
the anatomy of one of them, confirms the non-existence of the 
operculum and sustains the separation from Magilus. 
On the other hand, that experienced conchologist, Mr. G. B. 
Sowerby, in his introductory remarks upon the genus Magilus, 
in Conch. Iconica, xviii, 1872, unites Leptoconchus with that 
genus. He says: 
“The habits of this genus are very curious. The young fry, 
after a short period of free locomotion, seems to find its way 
into some hole in a growing madrepore, and then to become 
stationary ; but as the substance grows around it, it would soon 
become enclosed unless the growth of the shell kept pace with 
that of the madrepore. In order, therefore, to keep its aperture 
close to the surface, the two lips are extended in the same direc- 
tion in the form of an irregular tube. The Magilus leaves its 
