626 



MOLLUSC A. 



JHollusea. extremity spiral. Eyes rather behind the tentacula. 

 ""Y* ' Penis exserted on the right side of the neck, imme- 

 diately behind the eye. Cloak large in proportion to 

 the size of the foot. We have termed the genus Yelu- 

 tina, bestowing on the species the trivial name vul- 

 garis. 



The fourth FAMILY includes the Neritae of Linnaeus, 

 distinguished by the oblique straight pillar lip, and 

 semicircular aperture, closed by an operculum. Two 

 of the genera of this family, Natica and Nerita, are 

 marine, while the Neritina, represented by the Nerita 

 , fluviatilis of Linnaeus, lives in fresh- water streams. 



The SECOND TRIBE includes the spiral canaliculated 

 univalves of conchologists. The aperture of the shell 

 at its anterior margin is formed into a groove or canal. 

 This structure is occasioned by the anterior margin of 

 the cloak being produced over the aperture of the gills, 

 for the purpose of acting like a syphon or tube, to 

 convey the. water to and from the branchial cavity. 

 The species are considered as oviparous, with distinct 

 sexes in separate individuals. 



The first Family includes the genus Conus of Lin- 

 naeus. The animals are furnished with a long probos- 

 cis and tentacula, the latter bearing the eyes near the 

 summit on the outside. The lid is placed obliquely on 

 the foot, and is too small to fill the mouth of the shell. 

 The species, which nearly amount to two hundred in 

 number, are all inhabitants of the seas of warm coun- 

 tries. They are now arranged under the genera Conus 

 and Terebellum, 



The second Family, represented by the genus Cy- 

 prea, contains likewise many species. The cloak of 

 the animal is sufficiently large to admit of its extension 

 over the surface of the shell. The animal casts its 

 shell as it increases in size, and forms a new one suited 

 to its dimensions, as we have formerly stated. When the 

 shells are obtained before they have received their ex- 

 ternal coat, they have been regarded as new species. 

 The foot is destitute of a lid. 



The third Family consists of the genus Ovula of 

 Bruguiere. The animals of the different species are 

 unknown. The shells have been distributed into the 

 following genera by Montfort Ovula, Calpurna, and 

 Volva. The last includes a British shell, the Eulla 

 patula of Pennant. 



The fourth Family includes the Volutae of Linnaeus, 

 The genera, which are the following, appear to be des- 

 titute of a lid. Voluta, Oliva, Cymbium, Marginella. 

 Cancellaria, Colombella, Mitra Ancilla, Volvaria, and 

 Tornatella. 



The fifth Family is represented by the genus Bucci- 

 num of Linnxus. The canal is short, scarcely produ- 

 ced beyond the anterior margin of the lip, and bent to- 

 wards the left. All the animals which have been exa- 

 mined are furnished with a retractile proboscis. The 

 eyes are situated at the external base of the tentacula ; 

 and the foot is furnished with a lid. The following 

 genera have been established in this family : Buccinum, 

 Eburna, Dolium, Harpa, Nassa, Purpura, Cassis, Mo- 

 rio, Terebra, Cerithium, and Potamida. In the two 

 last the head is furnished with a hood, of which the 

 former genera are destitute. 



The sixth Family consists of the genus Murex of 

 Linnaeus. The canal of the aperture is straight, and 

 more or less produced. The inhabitants exhibit nearly 

 the same form as those of the preceding family. The 

 following genera appear to be formed on permanent 

 characters : Murex, Typhis, Ranella, Fusus, Pleuroto- 

 ma, Pyrula, Fasciolaria, and Turbinella. 



The seventh Family includes the Strombi of Lin- Moiiunei. 

 na?us. These possess a canal, which is short, and either s - ,-^- / 

 straight or bent towards the right. The outer margin 

 of the aperture is expanded with age, and exhibits a 

 second canal, generally near the former, for the passage 

 of the head. The following genera belong to this fa- 

 mily : Strombus, Pterocera, Rostellaria. 



The THIRD TRIBE is represented by the Helix halio- 

 toidea of Linnaeus, now constituting the genus Sigara- 

 tus. 



The foot of the animals belonging to this family, or 

 rather of the species which constitutes the type, is oval, 

 with a duplicature in front. The cloak is broad, with/' ' 

 an indentation on the left side, in front, leading to the 

 branchial cavity. A ring of transverse muscles unites 

 the cloak with the foot. On the back is placed the 

 shell, which does not appear on the outside, as it i 

 covered by a thick cuticle. It is lodged in a sack, and 

 united by a muscle, which adheres to the pillar. The 

 hood is produced, at each side, into a flattened tenta- 

 culum, with an eye at the external base. The anus is 

 situated at the branchial indentation on the left side. 

 The penis is situated on the right side of the neck. It 

 is external, with a crooked blunt lateral process near 

 its extremity. 



The mouth is in the form of a short proboscis. The 

 tongue is armed with spines, and is long and spirally 

 folded. The salivary glands are large. The stomach 

 is membranaceous, giving off the intestine near the 

 cardia. The intestine makes two folds. The liver, with 

 the testicle in the male, and the ovarium in the female, 

 occupy the posterior part of the body, under the spire 

 of the shell. Two species are natives of Britain. 



1. Sigarelus halioloidea. The tentacula in this spe- 

 cies are short and flat, and the foot rounded behind. 

 It is figured imperfectly by Montagu in Teslacea Bri- 

 tannica, vignette 2. fig. 6. It occurs frequently on va- 

 rious parts of the coast. 



2. Sigarelus lentaculatus. The tentacula are produ- 

 ced and filiform. The foot pointed behind. This spe- 

 cies was discovered by Montague at Kingsbridge, De- 

 vonshire, in 1809, and described and figured by him in 

 Linn. Trans, vol. xi. p. 1 86. Tab. xii. fig. 5 and 6. 



The animals of this order were formerly valuable in an 

 economical point of view. Many of them yield a rich 

 dye, which was much sought after by the ancients. This 

 was chiefly extracted from the animal of the Murex 

 Brandaris, and was termed Purpura. But it is like- 

 wise furnished by the animals of Purpura lapillus, Sea- 

 laria clathrus, and Planorbis corneus. Since the in- 

 troduction into Europe of the Cochineal insect, the use 

 of this dye has been superseded, so that we are now in 

 a great measure ignorant of the process which the an- 

 cients employed to extract it. 



The Pectinibranchias, although no longer sought 

 after as furnishing colour for enriching dress, are still 

 in estimation as articles of food. The Periwinkle is 

 frequently gathered by children in this country, as well 

 as the Nerita littoralis, and eaten when boiled. The 

 welk and buckie are likewise sought after. All these 

 animals are extensively employed as baitsfor catching fish. 



VI. ORDER SCUTIBRANCHIA. 



This order was instituted by Cuvier for the reception Srmibran- 

 of animals whose general form and respiratory organs chia - 

 are similar to the Pectinibranchiae, but which differ, in 

 his opinion, in so many other particulars, as to warrant 

 their separation. They chiefly belong to the old genera, 

 Halyotis and Patella. 



