210 



MUSEUM OF ANIMATED NATURE. 



[Tbochida 



and, coniequenUy. the de«r»blene«i that P«'«»»; 

 who have the opportunity »hould make coloured 

 drawing! from the hvinif animals, m a meang of 

 exTine a correct idea of the form and tinU of the»e 

 mollusks. before contracted and discoloured by the 

 alcohol in which they are generally preserved. 



ORDER HETEROPODA. 



Thx mollu»k» of thi» order are distinguished by the 

 ttructure of the fool, whi.-h, instead of forming a 

 horizontal disc, is compressed so as to constitute a 

 Tertical mascular paddle, serving as a fin. At the 

 edge of this, in many species, is a dilatation in the 

 fora of a hollowed cone, representing the disc in 

 other orders. The branchia;, which are plume-like 

 turts, are situated on the hinder pait of the back, 

 directed forwards; and immediately behind them 

 are the heart, the liver, and other viscera. The body 

 is gelatinous and transparent, with a muscular in- 

 vestment, elongated and generally terminating in 

 a compressed tail. Tlie mouth is furnished with a 

 muscular tube, and a tongue armed with minute 

 hooks. In swimming, the body is generally reversed, 

 the paddle-like foot being uppermost, the back 



downwards. ,,...■ .u 



These animals are capable of distending their 



body by filling it with water, in a manner not very 



clearly ascertained. . , . n 



Cuvier observes that Forskal comprehended all 



the species under the genus Pterotrachea, which is 



now greatly subdivided. 



2675. — Tbk Mediteeba.vian Cabiitabia. 



(Carinaria Mediterranea). In this genus the 

 branchia, the heart, the liver, and other organs 

 appear as if distinct from the general mass of the 

 body, and are protected by a delicate shell, some- 

 what resembling that of the Paper Nautilus (Argo- 

 nauta), seen in our iigure as reversed, the back 

 being downwards. 



This shell is no protection to the body generally, 

 being too small for the reception of the animal. 

 The general form of the animal is subcylindrical 

 and elongated. The whole ma-s is transparent, and 

 dotted with elevated points. The tail is furnished 

 above (or below, as the animal floats) with a sort 

 of fin, which performs the part of a rudder. 



The foot is a reddish, thin, compressed, and fan- 

 like paddle, beautifully reticulated by muscular 

 fibres crossing each other ; and furnished with a sort 

 of sucker, by means of which it cannot be doubted 

 that the moUusk is enabled to adhere to rocks or 

 stones, thus mooring itself whilst reposing at the 

 bottom of the sea. 



The mouth is a retractile muscular tube, fur- 

 nished with a rasp-like tongue, and the course of 

 the oesophagus, stomach, and alimentary canal is 

 easily seen through the transparent parietes of the 

 body. 



Referring to Fig. 2675, a shows the situation of 

 the oesophageal ganglion ; ft, the eye ; c, the head ; 

 d;the retractile tube of the mouth; e, the tenta- 

 culum; /, the digestive tube; g, the shell, con- 

 taining the organs of respiration, &c. ; /(, the poste- 

 rior or rudder fin; t, the ventral fin; A, the sucker 

 of the ventral fin ; II, the nerves. 



The present species of Carinaria is a native of the 

 Mediterranean, and specimens have been taken in 

 the Indian Ocean : hence it would appear to be 

 very widely spread. There are, however, others, as 

 C. Cyrabium, C. fragilis, &c., all natives of warm 

 latitudes. Fig. 2676, copied from the Iconograpliie 

 ofCuvier's' Animal Kingdom,' represents Carinaria, 

 with the back uppermost. It is tnere denominated 

 C. Cymbium ; but in all probability it is C. Medi- 

 terranea. 



2677. — Pbboh's Atlakta 



{Atlanta Peronii). Peron's Atlanta is a minute 

 mollusk, as transparent as crystal, with a most deli- 

 cafe shell spirally rolled on itself, and not unlike an 

 ammonite m form, inhabiting the Indian seas. 

 Referring to Fig. 2677, a represents this mollusk, of 

 the natural size. M. Lamanon thought that in this 

 mollusk he had discovered the original of the fossil 

 ammonites (' Voyage de La Peyrouse,' iv. p. 134, pi. 

 63) ; but in this view he was decidedly mistaken, 

 as it is incontestably proved that those fossil shells 

 belonged to cephalopodous moUusks. 



2678.— Thb Fibola 



(Firola Frederici). Excepting that there is no 

 shell, the Firola closely approaches to Carinaria : 

 the mouth is situated at the extremity of a long 

 proboscis; and at the end of the tail along jointed 

 thread is often to he observed, the nature of which, 

 says Cuvier, is not ascertained. Forskal considered 

 it a distinct parasitic animal. The Firolae are com- 

 mon in the seas of the warm or temperate latitudes, 

 and are remarkable for their extreme transparency, 

 vrhich is often interrupted by golden spots. 



From their delicacy, which renders them liable to 

 mutilation, it is not very easy to procure perfect 

 specimens of these singular mollusks, and conse- 

 quently the determination of the species is not al- 

 ways practicable. 



From the genus Firola Lesueur separates two 

 others, Firoloida and Sagitella, but upon very 

 trifling grounds. 



ORDER PECTINIBRANCHIATA. 



The Pectinibranchiata form the most extensive di- 

 vision by far of the Gastropodous mollusks, com- 

 prehending almost all spiral univalves, and many 

 simply conical shells. The branchise consist of 

 numerous leaves or strip ranged in parallel order 

 like the teeth of a comb, and are attached in one, 

 two, or three lines, according to the genera, on the 

 ceiling of the pulmonary cavity, which occupies the 

 last whorl of the shell, and opens between the edge 

 of the mantle and the body. A great difference 

 exists between the Pectinibranchiata, in the pre- 

 sence or absence of a tube formed by a prolongation 

 of the edge of the pulmonary cavity of the left 

 side, and which emerges through a canal or notch 

 in the shell, in order to enable the animal to carry 

 on aquatic respiration while shrouded in its domi- 

 cile. There is another point of distinction between 

 these mollusks, viz. that some are destitute of an 

 operculum for closing the mouth of the shell, and 

 moreover they vary in the fringes and other append- 

 ages of the head and body. In all, however, there 

 are two tentacles, and two eyes, supported sometimes 

 on peculiar peduncles. The mouth is trumpet- 

 shaped, more or less produced, and furnished with 

 a tongue armed with minute hooks, and so forming 

 a rasp capable, by repeated working, of piercing the 

 hardest bodies. 



The Pectinibranchiata are ranged into many fa- 

 milies, according to the form of their shells, which 

 appear to have a constant relationship to that of the 

 animals themselves. 



Family TROCHID.ffi. 



The mollusks of this family, according to Cuvier, 

 are distinguished by the shell having an entire aper- 

 ture, without notch or canal for a mantle siphon, or 

 pulmonary tube, the animals being destitute of such 

 siphon ; and by the possession of an operculum, or 

 some organ in lieu of it. 



2679. — The Obelisk Tbochbs 



{TrocJtus obeliscus). The genus Trochus is cha- 

 racterized by a shell of which the angular aperture 

 approaches at its external border more or less to the 

 totality of a quadrangular figure, and is on an ob- 

 lique plane with reference to the axis of the shell, 

 because that part of the border next the spire ad- 

 vances more than the rest. The greater number of 

 these animals have three filaments on each side of 

 the mantle, or at least some appendages at the sides 

 of the foot. The species are very numerous ; they 

 are marine, and feed upon plants ; their range is 

 very extensive, few seas being without some of 

 them. They are found at various depths, from the 

 surface to lorty-five fathoms, creeping on rocks, 

 sandy beds, masses of sea-weed, &c. M. Deshayes 

 enumerates a hundred and three existing species, 

 but this is under the mark. 



The Trochus obeliscus is a native of the Indian 

 seas ; it was found by MM. Quoy and Gaimard at 

 Tonga. The shell is conico-pyramidal, coloured 

 with green and white ; the whorls are more or less 

 tuberculate, nodose, obliquely furrowed across ; the 

 lower surface is planulate. The mollusk has stout 

 short tentacles : the eyes are on large pointed pedi- 

 cles ; the muzzle is wide, with a black riband near 

 its border ; the head is dotted with greenish ; the 

 foot is yellow below, and thickly sprinkled above 

 with dusky brown. The edge of the mantle is va- 

 riegated with brown and greenish ; the fringes of 

 the foot are white. 



Referring to Fig. 2679, a shows the anterior part 

 of the mollusk, and a portion of the operculum, 

 which is visible at the lower part of the figure ; 4 is 

 the-operculum removed to show its structure. 



2680. — The Impebiai. Tbochus 



(Trochus imperiidis). This is a very rare species, 

 and has hitherto been found only at New Zealand. 

 Quoy and Gaimard never obtained more than one 

 living specimen, of small size, which was found in 

 the Passe des Fran^ais, Tasman's Bay. The shell 

 was covered with calcareous incrustations and ma- 

 rine plants, indicating the indolent habits of the 

 animal. 



The shell is orbicularly conical, the apex obtuse ; 

 the whorls turgidly convex, squamoso-radiate at the 

 margin. Colour above violet brown, white below. 

 In the mollusk the muzzle is elongated in the form 

 of a proboscis ; the tentacles are short ; the ocular 

 peduncles stout and obtuse. The operculum is oval. 



smooth, and whitish. Referring to Fig. 2680, a tt- 

 presents the anterior part of the animal seen from 

 above ; ft, the inside of the operculum ; c, the out- 

 side of the same. 



2681. — TiiK Pebspective Solabium 

 {Solarium perspectivwn). Trochus perspectivus, 

 Linn. The genus Solarium is distinguished by the 

 spire of the cone being very wide ; the base presents 

 an extensive umbilicus, in which the eye may follow 

 the inner border of all the whorls, marked with a 

 crenulated cordon. 



The species included in this genus have been 

 found in the seas of warmer latitudes. They occur 

 respectively in the Mediterranean, the Indian Ocean, 

 in the South Seas, off the coasts of Tranquebar and 

 those of New Holland. Most appear to be littoral 

 in their habits, keeping near the shore, on banks or 

 rocks covered with marine vegetation. Upwards 

 of twelve species are recorded. 



In Solarium perspectivura the spell is orbicu- 

 larly conoid, longitudinally striated, yellowish white, 

 with articulated belts of white and brown near the 

 sutures ; the notches of the umbilicus are small. 



The mollusk has a large foot widened in front, 

 with a very strongly developed marginal furrow. 

 The head presents a large escutcheon ; the tentacles 

 are short and stout ; at their base are placed the 

 eyes on short peduncles. The operculum is large, 

 oval, and membranous. Referring to Fig. 2681, a 

 represents the front view of the shell ; b, the shell 

 as seen from below ; c, the operculum ; d, the an- 

 terior part of the animal. 



2682. — The Vabieoated Solabicm 

 (Solarium variegatum). This species, of which 

 specimens were procured by MM. Quoy and 

 Gaimard in Carteret Harbour, New Ireland, is of 

 small size, with an orbiculate convex shell trans- 

 versely sulcated, longitudinally striated, variegated 

 with white and bay. The umbilicus is patulous and 

 crenulated. 



This mollusk is remarkable for an operculum of 

 most singular form, which it carries at the posterior 

 part of the body, and which diifers from that of all 

 other species. Previously to the discovery by MM. 

 Quoy and Gaimard, with respect to the mollusk to 

 which it belonged, it had been known to concholo- 

 gists by the account of M. de Roissy, but all was 

 uncertainty as to the species to which it was to be 

 referred. It is a long solid calcareo-membranous 

 cone, carrying membranous lamellae spirally 

 throughout its length. The interspaces appear as 

 if ribanded. It does not enter completely into the 

 shell, but well fills the aperture. At Fig. 2683, a 

 represents the animal and shell of Solarium varie- 

 gatum, together with the operculum seen from be- 

 low ; 6, the operculum removed. 



The fossil Trochi and Solaria are very numer- 

 ous ; and as we have unfortunately so little to say 

 of the habits and manners of the recent species, it 

 may not be amiss to enter into the distribution of 

 the fossil species, as recorded by different geologists, 

 to whom the study of conchology is of the highest 

 importance. We shall take Trochus and Solarium 

 separately. 



Trochus. — M. de Blainville states that Lamarck 

 enumerates nine fossil species, and Defrance fifty- 

 six, eleven of which the last-mentioned zoologist 

 considers as analogous : six are from Italy, and 

 thirty-eight from Grignon. 



Mr. G. B. Sowerby observes that the fossil spe- 

 cies, which are rather numerous, belong to the 

 newer formations, such as the crag, the calcaire 

 grossier, and the green-sand : they are also, he 

 adds, found in the London clay, and he remarks 

 that he has reason to believe that some species oc- 

 cur so low down as the lias. 



The number of fossil species of Trochus recorded 

 by M. Deshayes in his tables is seventy (tertiary) ; 

 and of these Trochi magus, fagus, cingidatus, ag- 

 glutinans, Adansoni, conulus, cinerarius, conu- 

 loides, Matoni, zizypbinus, strigosus, and obliqua- 

 tus, are given as species found both living and fossil 

 (tertiary). Trochus crenulatus is noted among those 

 species which are found in more than one tertiary 

 formation, but does not occur in the living and fos- 

 sil list. Mr. Lyell, however, under the head of 

 ' Fossil Shells, collected by him in Ischia, and named 

 by M. Deshayes,' mentions Trochus crenulatus as 

 one of four shells sent to him from Ischia, all of re- 

 cent species. Mr. Lyell enumerates also, among 

 the fossil shells from the western borders of the 

 Red Sea, collected by Mr. James Burton, and 

 communicated by Mr. G. B. Greenough, Tro- 

 chi maculatus, virgatiis, and mauritianus^ all de- 

 scribed as recent by Lamarck. Among the fossil 

 shells collected by him at Sienna, he notices Tro- 

 chus fermonii, and a new species, with its colour. 

 (' Principles of Geology.') 



That Trochus occurs below the chalk appears 

 Irom Dr. Fittoii's valuable list, where Trochus Sedg- 

 wickii is recorded both from the upper green-sand 



