Strombus.] 



MUSEUM OF ANIMATED NATURE. 



243 



Cuvier, followine; Lamarck, divides the Strombidae 

 into thiee principal genera : Strombus proper, Pte- 

 roceras, antl Rostfllaria. 



In Strombus proper the outer lip dilates into a 

 wing, more or less extensive, but not divided into 

 digitations. The loot is proportionally small, and 

 the tentacles carry the eyes on a lateral peduncle, 

 thicker than the tentacle itself. The operculum is 

 horny, long, and narrow, and carried on a slender 

 tail. 



In Pteroceras the wing, or dilated outer lip, is 

 divided in the adult into long and slender digita- 

 tions, according to the species. The animal is the 

 same as that of Strombus. 



In Rostellaria the sinus of the externa! edge is 

 contiguous to the canal, and there is generally a 

 second canal, reascending along the spire, and 

 formed by the external lip, and by a corresponding 

 contniuation of the columella. 



Fig. 2812 represents a species of Strombus (Pte- 

 roceras lambis), extricated from the shell and dis- 

 sected (female) : a, the foot seen at its anterior part 

 with its groove ; 6, the operculum fixed at its pos- 

 terior division ; c, the ocular peduncles or tubes 

 with the slender tentacles; rf, the proboscis open 

 to show the tongue ; e, the cerebral ganglion, be- 

 hind which are two long salivary glands ; f, the 

 oesophagus entering a large stomach ; g, the 

 stomach partially opened, and showing the entrance 

 of the oesophagus ; /(, the intestinal canal ; i, k, I, 

 and 771, other internal organs ; n, the respiratory 

 siphon ; o, the large branchia with its vein which 

 goes to the heart ; p, small and rudimentary bran- 

 chia; q, the heart; r, the liver. 



2813. — The Broad-winged Strombus 



(Strombus latissimus). As an example of the genus 

 Strombus we select this remarkable species, which 

 is by no means common. It is a native of the In- 

 dian seas, and grows to a large size, often mea- 

 suring from eight to twelve inches in length. The 

 shell is turbinated and ventricose, smooth on the 

 back, but somewhat wrinkled on the wing ; the 

 spire is short; the wing or external lip very broad, 

 rounded above, and extending beyond the spire. It 

 is very thick, but becomes thinner at the margin, 

 which is sharp anteriorly. The general colour is 

 orange-brown variegated with white ; the aperture 

 is smooth and white with a roseate tinge : a repre- 

 sents the shell seen from above ; 6, the same seen 

 from below. 



2814. — Thk Scorpiom Pteroceras 



(Pteroceras Scorpius). The shell in this species is 

 somewhat oval, tuberculate, and transversely ru- 

 gose. The outer lip or wing is divided into seven 

 slender knotted or curled digitations, of which those 

 in the centre are the shortest. The general colour 

 is while spotted with rufous ; the aperture is viola- 

 ceous red, with the rugae white. 



2815. — The Chisese Spindle 



(Rostellaria rectirostris). In some species of the 

 genus Rostellaria the outer lip is digitated, as in 

 Rostellaria Pes Pelicani, the type of the genus 

 Aporrhais of some authors; some have dentilations 

 only on the edge, with a straight canal ; others, 

 constituting the genus Hippocrenes of De Mont- 

 fort, have the external lip dilated, but not denti- 

 lated. 



The present species has the lip dentilated. 



The Chinese spindle is a rare shell, and specimens 

 with the long slender beak unmulilated are seldom 

 to be met with in collections. A specimen exists 

 in the British Museum in which this part is perfect, 

 or nearly so, and recurved. 



The shell is fusiform, with an acute apex; the 

 whorls are rather convex. In young specimens the 

 dentilations of the outer lip are either wanting or 

 very small. The lip terminates in an elegant canal 

 or volute at the bottom of the spire, and is indicated 

 at the letters a, a. General colour brown ; darker 

 on the inside of the outer lip. It is a native of the 

 Indian seas, and has been dredged up in the Straits 

 of Macassar. 



The StrombidsB are carnivorous in their habits, 

 and tenant the seas of the hotter latitudes; many 

 are Indian, some are found at the equator. Two 

 species of Rostellaria, viz. R. Pes Pelicani, and R. 

 Pes Carbonis, are natives of the Mediterranean and 

 other European seas. 



The number of species is very considerable ; and 

 many, as the huge Strombus Gigas of the West 

 Indies, attain to enormous dimensions. 



It is a curious circumstance that in several of the 

 Strombidae pearls have occassionally been discovered, 

 and also, it may be added, in some others of the 

 turbinated te^taceans. We need scarcely observe 

 that pearls consist essentially of the same material 

 a-s the substance called nacre, or mother-of-pearl, 

 with which the shell is lined. In pearls this nacre 

 18 found to be deposited in concentric layers round 

 Vol. II. ^ 



some minute extraneous sub.stance, irritating the 

 mollusk ; such at least is generally the case. 



Mr. Wood, in his ' Zoography,' informs us that he 

 saw a pearl of a pink colour, taken from the body 

 of the mollusk of a Strombus Gigas, dredged up near 

 the island of Baibadoes, where this species of 

 " shell-iish" is served up at table. Its weight was 

 twenty-four grains, but unfortunately it was not 

 perfectly round, a circumstance which rendered it 

 less valuable. Though thousands of "shell-fish" 

 are annually brousrht to the market in that part of the 

 world, yet Mr. Wood states that he was acquainted 

 with only four instances of pearls being found, not, 

 as he supposes, because they are really scarce, but 

 because the negroes who clean the fish do not take 

 any trouble to look for them, but perform their 

 work without consideration ; hence, as he has reason 

 to believe, many pearls with the refuse of the fish 

 are thrown back into the sea. With respect to the 

 genus Strombus, M. de Blainville enumerates fifty- 

 two recent species; the Strombus Gigas occurring 

 also in a fossil state in tertiary deposits, but of the 

 genera Pteroceras and Rostellaria the numbere are 

 limited. 



The fossil species of Strombidae are not met with 

 so frequently as those of other groups. M. Des- 

 hayes gives the number of Strombi as nine, includ- 

 ing the Strombus Gigas. Of the Rostellariae M. 

 Deshayes records eight species in the tertiary strata. 

 Mr. Lea describes two species from the Claiborne 

 beds, Alabama ; Dr. Mautell one species from the 

 sandstone of Bognor, and two species from the 

 Thanklin sand. Dr. Fitton (see his 'Strata below 

 the Chalk ') also enumerates some species. 



ORDER TUBULIBRANCHIATA (Guv.). 



CuviERconsidersthattheTubulibranchiata, although 

 they are closely related to the Peclinibranchiata, 

 ought to be separated from the latter, because their 

 shell, being in the form of a tube, more or less 

 irregular (the commencement of which alone is 

 spiral), is firmly attached to other bodies; from 

 which cause, when once fixed, they have no power 

 of shifting their station; hence are they necessarily 

 bisexual, each individual continuing the race. 



He divides this order into three genera, Vermetus, 

 Magilus, and Siliquaria. 



With respect to Magilus, it was placed by La- 

 marck among the Annelids, in the family Serpu- 

 lacea; but M. de Blainville appreciated its relation- 

 ship to Siliquaria and Vermetus, between which it is 

 placed by Cuvier. 



M. Rang states that, when he was seeking the 

 animal in India, he was stiuck with the analogy 

 which the genus presents, not only to Vermetus, 

 but also to some of the Pectinibianchiata; an 

 analogy, as he observes, the more remarkable when 

 a young individual, the shell of which has not yet 

 become tubular, is examined. 



The young shell of Magilus is, in fact, very simi- 

 lar to that of Leptoconchus striatus, which, as we 

 have previously said, becomes imbedded in masses 

 of coral or madrepore (Meandrina, &c.), in which 

 Magilus also occurs ; and Dr. Riippell suspects that 

 M. Rang might have mistaken the Leptoconchus 

 for the young of Magilus. Between these shells 

 there are, he adds, certain clear distinctions. In 

 Leptoconchus the margins of the shell are always 

 disunited, the contrary in Magilus ; the latter has 

 an operculum, the former has none. The proboscis, 

 moreover, in both is different, and the mollusk of 

 Magilus has a siphon, which is not present in Lep- 

 toconchus. Both tenant the masses of Meandrina 

 in the Red Sea. (See ' Proceeds. Zool. Soc' 1834, 

 and 'Trans. Z. S.' vol. i.) 



2816.— The Magilus 



(Magilus antitjuus). The Magilus is here repre- 

 sented in its young condition, before the evolution 

 of the tube. 



2817.— The Magilus 



(Magilus antiqwis'). In this specimen the long 

 sinuous tube indicative of age is very remarkable. 

 We shall proceed to explain the manner in which 

 this development takes place, and which is very in- 

 teresting. First let us refer to the young shell 

 (Fig. 2816); we find it of a delicate fragile struc- 

 ture, covered with a thin epidermis, of a ventricose 

 figure, with a short spire of three or four turns, and 

 a patulous aperture, the lip being produced ante- 

 riorly so as to form an angle. It is in this stage a 

 regular spiral univalve. We must now suppose the 

 young Magilus to have taken up its abode in tome 

 recess or fissure of the madrepore, itself in a state of 

 growth, from the secretion of the living polypes. 

 With the increase of the madrepore, in order that it 

 may not be blocked up, and so destroyed, it has to 

 put some plan in operation so as to preserve its 

 I aperture on a level with the surrounding mass, 

 I thereby securing free admission to the water. The 

 ! plan dictated by instinct, for it cannot shift its 



(juarters, is to add to the margins of its shell, build- 

 ing up layer after layer, according to the growth of 

 the madrepore, and in that direction which circum- 

 stances may determine, and which will consequently 

 vary. In proportion as the mollusk adds to the 

 tube, so it advances forwards from the spiral shell, 

 which it quits, filling it up with compact calcareous 

 matter, almost crystalline in structure, and re.sides 

 in the tube ; and, as this continues to be lengthened, 

 so does the animal continue to advance, filling up 

 the unoccupied space behind with the same material. 

 Thus, then, as necessity requires, the mollusk of the 

 magilus carries out its tube, to which the operculum 

 is so adapted as toactasabarrier against the assaults 

 of enemies — a protection the more necessary as it 

 cannot change its position. It would appear that 

 only one species is recognised, viz. Magilus anti- 

 quus : it is of a whitish colour. 



We now turn to the genus Vermetus. 



Let our reader fancy a group, of serpentiform 

 tubes, all intertwined together, such as poets de- 

 scribe the hair of Medusa, covering old shells or 

 stones, and he will have a good idea of the Vermeti. 

 Such a group is represented at Fig. 2818, in which 

 several species are depicted, like a knot of snakes, 

 coiled in fantastic wreaths, but elevated on their 

 tails, and dancing to the music of the charmer, who 

 had 



" Then framed a spell when the work w.is done, 

 And changed the * living' wreaths to stone." 



The Vermeti, says Cuvier, have a tubular shell, 

 of which the whorls at an early period form a sort 

 of spiral shell, but which alterwards become pro- 

 longed into a tube more or less irregular, or twisted 

 like the tubes of Serpulae (certain annelids). This 

 contorted shell is usually fixed by being intertwined 

 with others of the same species, or in consequence 

 of being partially enveloped by lithophytes. The 

 mollusk never creeps, and therefore has no foot 

 properly so called ; but that part which in ordinary 

 gasteropods may be called the tail is doubled under- 

 neath, advancing before the head, and having its 

 extremity dilated and furnished with a slender 

 operculum. When the animal withdraws itself this 

 mass closes the orifice of the tube : it has sometimes 

 peculiar appendages, and in some species the oper- 

 culum is spiny. The head is obtuse, with two mo- 

 derate tentacles bearing the eyes at the outer side 

 of their base; the mouth is a vertical orifice, be- 

 neath which, on each side, appears a filament hav- 

 ing all the appearance of a tentacle, but which in 

 reality belongs to the foot. The branchiae Ibrra 

 only a row along the left side of the respiratory 

 cavity. 



The species are rather numerous, but not very 

 distinct. Linnaeus, guided by the form of the 

 shells, placed the Vermeti with the Serpulae ; and 

 the Vermilise of M. Lamarck, which are identical 

 with the Vermeti, are left by that naturalist in the 

 situation assigned by Linnaeus. Such are the Ser- 

 pula lumbricalis, Linnasus, and the Serpula tri- 

 quetra, with several others. 



As in the genus Magilus, the mollusk gradually 

 advances as it adds to its tube, so as to occupy the 

 more anterior portion only. 



In general the eggs of these mollusks become 

 fixed about the spot where they are exuded ; hence 

 we may easily understand how it happens that the 

 shells are generally found in groups; yet single 

 isolated specimens are not uncommon, the agitation 

 of the waves having scattered the eggs asunder, 

 and kept them suspended till at length they be- 

 come fixed upon a suitable basis. Some species, as 

 Vermetus lumbricalis, have the commencement of a 

 spire, the whorls of which rise perpendicularly ; 

 others take a horizontal direction with the orifice 

 only elevated. 



2819. — The Dentilated Vermetus 

 ( Vermetus dentiferus). This species was procured 

 by MM. Quoy and Gaimard during the voyage of 

 the Astrolabe, a is the shell ; b, the mollusk. It 

 occurs on shells along the coast of New Holland, in 

 Shark's Bay, &c. 



2820. — The Lumbeicoid Vkbmetus 

 (Vermetus lumbricalis). It is this species of which 

 a group, fixed on a shell, is represented at Fig. 

 2818; and, from the varied contortions and inter- 

 lacings of the individuals, most picturesque is their 

 general aspect. A similar group in the British 

 Museum has olten arrested our attention. 



We now turn to the genus Siliquaiia. 



The Siliquaria; resemble the Vermeti in the ge- 

 neral aspect of the mollusk, in the ibrm of its head, 

 in the position of the operculum, and in the tubular 

 and irregular structure of the shell. There is, how- 

 ever, this remarkable distinction— the shell pre- 

 sents a slit or unfilled line throughout its whole, 

 following the direction of its flexures, and which 

 corresponds to a similar fissure in that part of the 

 mantle which covers the branchial cavity; along 

 one side of this fissure of the mantle runs the 



2 I 2 



