358 



Div. 2. MOLLUSCA.— GASTEEOPODES. 



Class 3. 



Fie- 1S4.— Mures tcnuispiu. 



The Murex, Linn.*— 

 Embraces all shells whose canal is elongate and straight. I have found in the animals of all the sub. 

 genera a proboscis ; approximated long tentacula, with the eyes external at their base ; a horny oper- 

 culum, and no veil over the head : they otherwise resemble the Buccina, except in the length of the 

 siphon. Bruguieres di^^ded them into two genera, subsequently subdivided into others by Lamarck 

 and Montfort. 



Murex, Bnigf., are all shells with a salient straight canal, and with varices across the whorls. M. Lamarck 

 reserves this name specially to those in which the varices are not contiguous, so as to make two opposite rows. If 

 their canal is long and slender, and the varices are armed with spines, they belong to the Murex of Montfort. 



If the varices are merely nodulous, 

 they constitute his Brontes. Some, 

 with a canal of moderate length, 

 have projecting tubes between the 

 spinous varices which penetrate 

 the shell ; and these are the Ty- 

 phis, Montf. The Chicoracea of 

 the same have, instead of spines, 

 the varices garnished with plait- 

 ed leaves, torn or divided into 

 branches : their canal is long or 

 moderate, and their foliaceous 

 productions vary infinitely in 

 shape and complexity. Wlien, with 

 a moderate or short canal, the 

 varices are only nodulous, and when the base has an umbilicus, the shell becomes an Aquilla, Montf. We have 

 several species on our coasts. If there is no umbilicus, that marks the genus Lotorimn. Lastly, when the canal 

 is short, the spire raised, and the varices simple, the shell is a Tritonium. The mouth is generally grooved trans- 

 versely on both sides. AVe have some large species in.our seas. [The T. varlegaium is much valued by the inha- 

 bitants of some of the South Sea islands.] There are of them some with numerous, compressed, almost mem- 

 branous varices,— the Trophones, Montf. ; and in others they are much compressed and very prominent, but few 

 in number.t 



M. de Lamarck separates from all the Murices of BrugTiiferes the Ranella, Its character is to have the varices 

 opposite, so that the shell is as it were girded with a border on two sides. Their canal is short, and the surface is 

 roughened only with tubercles. The margins of their aperture are furrowed. The Apolles, Montf., are merely 

 umbilicated Ranella?. 



i^)(*M*, Brug., includes all the shells of this family which have no varices. AVhen the spire is prominent, the 

 pillar without plaits, and the margin entire, this is the Fiistis of Lamarck, which Montfort has still further 

 restricted, for he reserves this name to such as have no umbilicus. The less elongated and more ventricose 

 species gradually approximate to the Buccina in their shape, and where they have an umbilicus, Montfort calls 

 them Lathires. The Slnithiolaria is another subgenus, distinguished by the inner lip being thickened and 

 spreading over the lower part of the last volution and the columcU.i, and in the adult the outer lip is thickened 

 and turned outward,— a character that connects them with the Murex. When the spire is raised, the columella 

 without plaits, and when there is near the top of the aperture, on its outside, a well-marked sinus or fissure, we 

 have the characters of I'leurotoma, Lain. When this sinus is wide and touches the spire, some have seized the 

 too slight distinction to make the genus Clavatula. When the spire is depressed, and the pillar without plaits, 

 these are the Pijrnla, L^ni., which are either umbilicated or not. Montfort separates from Pyrula the species 

 with a flattened spire, and which are striated within the mouth, to call them the Fulgnr. They are in some degree 

 Pyrula; with a plaited columella, and the plaits are sometimes even scarcely perceptible. Amid these dismember- 

 ments of the Fimis, Brug., we distinguish the Fasciolaria, Lam., by some oblique and distinct folds on the 

 columella, near the origin of the siphon. 



TKri/ju'/ZflT, Lam., arc likewise shells with a straight canal, without varices, distinguishable by having [from 

 three to five] prominent, compressed, transverse folds, all nearly equal in size, near the centre of the columella, 

 and which approximates them to the conical Volutae : in fact, they only differ by the superior elongation of the 

 sy phonal canal, [and in having an operculum, as well as a thickish epidermis]. 



The Strombusidjk {Siromlus, Linn.) — 

 Comprise tlic shells with a canal cither straight or bent to the right, the external lip of the aperture 

 l)ecoming, in its maturity, more or less dilated, and always marked with a sinus near the siphonal 

 canal, whence the head issues when the animal comes out. In the greater number this sinus is at some 

 distance from the canal. 



• Cocqunl Willi the family SipTionosioma of M. de Blaiiiville. 



t It is to be rcttrotted tlmt Cuvicr should have pvcn even the appcnrancc nf a saiietion to these new Kcnorn of Monlfurt.— Eo. 



