M L L U S C A. 



615 



digenous: 1. lubricus ; 2. obscurus; 3 lackhamentia ; 

 4. fasciatus. 



The species which are related to the Turbo bidens 

 perversus and mutcorum of Linnzus; constitute a very 

 natural family, which may be termed I'CPALEA. dis- 

 tinguished by the mouth being in general furnished 

 with teeth, or testaceous larainx, and the last whorl 

 nearly the same or less than the preceding. Perhaps 

 the most convenient way of dividing them is into two 

 cections, the first including the dextral, and the second 

 the sinistral shells. 



The dextral pupacea form three genera. The Pui'A, 

 as originally constructed by Lamark, was equally faul- 

 ty with many of the old Linnwan genera. As we have 

 restricted it to include dextral shells, with the animal 

 possessing four tentacula, with eyes at the tips of the 

 two longest, we can receive into it the miiscorum, tex- 

 dfHta'nx, and fiiri/ieri of Montagu. The genus O'hon- 

 dru* of Cuvier contains the tridens of Montagu. In 

 the genus CARYCHIVM, formed by Muller, the tenta- 

 cula are only two in number, with the eye* placed at 

 the base. It i* represented by the T. carychium of 

 Montagu. 



The sinistral pupacea form two genera. The 

 first, which i* the Clausilia of Draparnaud, contains 

 sinistral shells, with the animal furnished with four 

 tentacula, with eye* at the tips of the two longest. 

 To the pillar there is attached internally a twisted 

 plate. This contains the following British species, 

 pervcrta, nigricata lammata biplicala, and labiata. The 

 other genus, called VERTIGO, was formed by Muller. 

 The animal possesses only two tentacula, with the 

 eye* on their tip*. The T. vertigo is the type of the 

 genus. 



In the *bell* of the preceding genera, the margin of 

 the mouth is always thick and strengthened by a ring 

 when the animal it arrived at full growth, after which 

 the shell i* stationary in point of size. This is a cha- 

 racter peculiar to the terrestrial testacea. In the two 

 genera which follow the margin of the mouth is sim- 

 ple. 



VIII. VITIINA. Thi* genus was formed by M. Dau- 

 debard de Ferussac, and termed by him Helico-limax, 

 Draparnaud, to avoid the use of a hybrid name, sub- 

 stituted Vitrina. The -hell i* mcapaiile of containing 

 the animal. The margin of the shieKl i* double, and 

 the upper fold is divided into several lobes, which are 

 reflected on the surface of the shell. The Helix pellu- 

 cida of Muller is the type of the genus. 



IX. SLCCINKA. From the Helix succinea of Muller 

 (the putris of Montagu and Donovan, not of Lin- 

 naeus) Draparnaud ha* formed the genus Succinea. 

 The mouth i* large in proportion to the size of the 

 shell, and effuse at the base, with the outer lip thin, 

 and the pillar attenuated. We are at a lost to ac- 

 count for the conduct of Lamark in substituting a 

 new name for this genus without any apparent reason, 

 and thus adding to the synonimes with which the 

 science is already oppressed. Tne name first employ- 

 ed by Draparnaud, indicates one of the mot ktriking 

 character* of the type of the genus, whereas" the term 

 Amphibulina, ued by Lamarck, is founded on a mis- 

 take, and is apt to mislead. The Helix succinea, al- 

 though found in damp place*, is not amphibious. It 

 never enter* the water voluntarily. Indeed, Muller 

 *ay, " Sponte in aquam descendere nunquam vidi, e 

 contra quotie* etirn aquae iromisi, cont'estim egredieba- 

 tur." The same remark i* made by Montagu, and we 

 have often witnessed it* truth. 



X. ACHATINA. The mouth of the shell in this ge. 



nus nearly resembles the Bulimi, but the end of the Mollusc.', 

 pillar is truncated. The Buccinum acicula of Muller, 

 a native of England, belongs to this genus, and like- 

 wise the Helix octona of Linnaeus, erroneously consi- 

 dered as a native of Britain. 



XL CYCLOSTOMA. This genus is readily distin- Cyriost*- 

 guished from all the preceding by the circular aperture m - 

 of the shell, and the toot of the animal being furnished 

 with a lid or operculum. This genus may be regarded 

 as the type of a singular tribe of the terrestrial pulmo- 

 nifera. The pulmonary cavity opens upon the neck as 

 in many of the pectinibranchia. The sexes are like- 

 wise separate, the penis of the male being large and 

 muscular, but contained in the interior. The primary 

 tentacula have sub-globular highly polished extremi- 

 ties, which Montagu (Testacea Britannica, p. 345.) is 

 disposed to regard as eyes. The true eyes are placed 

 at the base of the tentacula on the outside, and arc ele- 

 vated on tubercles, the rudiments of the second pair. 

 The tentacula, though somewhat contractile, are inca- 

 pable of being withdrawn after the manner of the slugs 

 and snails. The C. elegans, the Turbo elegans, of 

 Montagu, is the type of the genus. 



. SECT. II. 



The aquatic pulmoniferous gasteropoda, which are in- Pulmoni- 

 cluded in this section, have all two tentacula, usually 

 flattened with the eyes at the internal base. The sexes 

 are united. The spawn in the form of a gelatinous 

 maw i* deposited on aquatic plants, under water. The 

 food consists of aquatic plant*. Although they reside 

 in the water, they are obliged to come to the surface to 

 respire, when they open the pulmonary cavity, and af- 

 ter remaining a short time, again close it nnd descend. 

 Like the genera of the preceding section, they admit of 

 distribution into two tribes. 



Tribe 1. This contain* those animals which are 

 naked, and which have been included in the genus 

 Onchidium. In this genus, the animals are furni-hed 

 with a cloak of more than ordinary thickness, which 

 cover* the whole of the upper part of the lx>dy. There 

 are two long tentacula on the head capable of being 

 withdrawn like tho-e of the slug. The snout is divided 

 into two broad appendages. Between the tentacula, 

 towards the right side, U the opening for the penis. 

 The anus is terminal, above which is the entrance to 

 the pulmonary cavity, and on the right is the opening 

 to the female organs, from which a groove runs towards 

 the right lobe of the snout. 



The mouth is destitute of proboscis or jaws. The 

 tongue is merely a cartilaginous plate grooved trans- 

 versely. The gullet is long in proportion with a villous 

 surface. There are three stomachs, each distinguished 

 by its peculiar characters. The first is a true gizzard, 

 covered internally with a cartilaginous cuticle, and it* 

 walls formed of two strong muscle? with connecting li- 

 gaments. The second stomach is funnel-shaped, with 

 prominent ridges, both on its external and internal sur- 

 face. These ridges at their origin, internally, are high- 

 est, and project considerably into the cavity, acting 

 like a valve in retarding the progress of the food. The 

 third stomach is short and cylindrical, covered inter- 

 nally with equal longitudinal fine ridges. The intes- 

 tine i* nearly of equal thickness throughout, and about 

 two and a half time-, longer than the body. The sali- 

 vary glands are much branched and pour their con- 

 tents into the entrance of the gullet. The liver in the 

 anima's of this genus i> distributed into three sep.ir.it'- 

 portions, each of which may be regarded a* a distinct 

 liver, an arrangement which is not known to take place 



