These shells are of such a tender nature, and their colours so evanescent or so feebly fixed, that they almost constantly present a mutilated and bleached appearance. This is not, however, uniformly the case; we have very recently had an opportunity of inspecting several specimens of a moderate size, that were brought from China, and from these we perceive that the Wentletrap, when in fine order, is of a pale testaceous or rather fulvous hue; and inclining sometimes to yellowish. In some few specimens the ground colour of the shell, instead of being uniform, appears sprinkled with pallid spots and dots of a rounded form. Sometimes we are assured the colour inclines to rufous, or a reddish tint. Lamarck has this shell of a pale fulvous colour, with the ribs as usual, white, for he adopts this as part of the leading character of the species; his expression is “pallide fulva; costis albis.”
The animal inhabitant of this shell has the head armed with two feelers, each ending in a setaceous thread or hair: the eye is placed upon the tentacula at the base of this thread or hair, and it has also a kind of trunk at the mouth, by means of which it searches for its food amongst the sand and weeds. It is supposed to be of a carnivorous nature, subsisting on other marine worms. It is considered rather as a littoral species, frequenting the little sandy bays and creeks among the breakers upon the lower parts of the sea shore, and is to be sought for with the most probability of success among the sea weeds or fuci that grow in the pools of water lying in these sunken rocks, because in such situations it is most likely to find protection against the intrusion of the boisterous element. Occasionally it is seen, though rarely, crawling on the sands at low water.
In a natural classification of the shell tribe, should we ever arrive at an arrangement of Conchology, so perfect as to deserve that epithet, it would be a task of some difficulty to fix the precise station of the Wentletrap; for in the order of nature it presents anomalies which cannot easily be reconciled, and few authors are agreed upon this subject even in the artificial arrangements which they have been induced to adopt. Thus Rumpfius makes it a Buccinum, Davila a Tuyau, Argenville places it as a Terebra (vis) and De Montfort Scalarus. In the Encyclopædia it is denominated Scalaria Pretiosa, and this name Lamarck retains.
The name of Wentletrap, by which this shell is now so well known, is derived from the Dutch Language, and signifies according to the technical phraseology of the Dutch architects in building, a winding stair case, or flight of stairs turning spirally round a central column, into which one end of every step is mortised as they ascend from the base upwards. The term Wentletrap, Wenteltrap, or as the Dutch sometimes call it, Wendeltrap,[[19]] is the name given by Rumpfius the Hollander to this shell, as a synonymous name with his latin term Scalare. It is an allusion, somewhat fanciful we must allow, to the disposition of the costal ridges upon this shell, and which when viewed laterally as they traverse or pass over the upper convexity of the whorls on each side, have the appearance of a flight of steps turning spirally round the body of the shell, just as a winding staircase would be carried spirally round a cone or sub-cylindrical body. The singularity of this species (for it is not a peculiarity or character even of the new genus Scalaria as established by Lamarck and Cuvier) consists in having the whole whorl of the shell, from the mouth to the summit, entirely unconnected, while in spiral shells the suture of the whorls is united throughout. The tube is perfectly detached from the mouth to the apex, and the whorls linked together only by means of the longitudinal ribs which traverse the tube at regular intervals, so that the only connexion of the whorls is at the junction of those ribs, which touching each other unite at that part which in regular spiral shells that have the whorls united, would be denominated the suture of the whorls.
Considering the very zealous propensity of some French Naturalists of the present day, and of their admirers in England, to create new genera upon every slight occasion, it becomes a matter of some astonishment that a character so very obvious as the disjunction of the tube from the aperture to the very summit should not have laid the foundation of a new genus, for the reception of this shell. Lamarck, however, places it at the head of his Scalaires, and one of the next species in succession is his Scalaria Communis, a shell perfectly well known by every Naturalist throughout Europe for nearly a century past under the name of Turbo Clathratus.[[20]] Nor is Lamarck singular in this very anomalous consolidation of shells so distant in this respect from each other; for Cuvier in his Règne Animal, after describing our present shell, the Linnæan Turbo Scalaris, as one of his Scalaires, and informing us it is distinguished by the whorls not touching each other, adds particularly that there is another species which has not that peculiarity, and that is the Turbo Clathratus. Nothing, however, can be more certain than that from this very circumstance these two shells are generically distinct from each other; Clathratus may be retained with the Linnæan Turbines, but Scalaris has nearly, if not entirely as much claim to the Serpula[[21]] as Turbo genus; which cannot be said of T. Clathratus. We shall for this reason allow the Wentletrap to remain where Linnæus has placed it, namely, among the Turbines; not perhaps without some hesitation, but if we did remove it, we should certainly prefer the institution of new genus for its reception, instead of wandering from one anomaly to another, as we must perceive would be the case in the present instance by following the example of Lamarck and Cuvier.
It may be lastly observed that the progressive growth of this extraordinary rarity may be determined by the greater number of the longitudinal ribs that pass over and surround the tube of the whorls, for at each increase the animal forms a new mouth to its shell: the new mouth as it is protruded and formed, appears like the former ones, entirely surrounded by a rim or ring, and it is these rings of the mouths as they are formed in succession, that constitute the ribs which appear to traverse the shell as it is increased in length, and consequently in the number of its rings. Shells of a large size exhibit sometimes as many as fifty or sixty of such rings surrounding the tube or spire at regular intervals.
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London. Published as the Act directs by E. Donovan & Mess.rs Simpkin & Marshall Dec.r 1 1822.