34 8 



MOLLUSCA. 



The Vaginulus, Feruss.* — 

 Has a dosc-fittcd cloak without a shell, extended OTer the \Yhole length of the body; four teutacula, 

 of which the inferior are somewhat forked ; the anus cjuite at the posterior extremity, between the end 

 of the cloak and that of the foot ; and the same orifice leads to the pulmonai7 cavity situated along 

 the right flank. The orifice of the male organ of generation is under the right inferior tentaculum, and 

 that of the female organ under the middle of the right side. These organs, as w^ell as those of digestion, 

 are very similar to those of tlie Snail. The genus Ijelongs to both Indies, and is much like our Slugs. 



The Testacell.e, Lam. — 

 Have tlie respiratory aperture, and the anus, near the posterior extremity ; their cloak is very small, 

 auu also placed there, and contains a small ear-shaped shell, which does nut equal one-tenth of the 

 length of the body. In other respects, these animals resemble our Slugs. 



One species is found abundantly incur soutliem 

 U, departments {Testacella haliotoidea, Diaparn.), 

 living under ground, and feeding principally 

 on earth-worms. M. de Fernssac has observed 

 that its cloak assumes an extraordinary develope- 

 rnent when the animal finds itself in too dry a 

 situation, and thus produces for itself a sort of 

 shade and shelter. 



[Tliere are some interesting: illustrations of the 

 habits of the Testacella^ in Loudon's Magazine 

 of Natural History, vol. vii.] 



The Parmacella, Cuv. — 

 Has a membranous cloak, with loose margins, situated [upon a gibbosity] in tlie middle of the back, 

 and containing, in its posterior part, an oblong flat shell, which exhibits the mere vestige of a spine. 

 The respiratory aperture, and the anus, are umler the right side of the middle of the cloak. 



The first known species was from Mesopotamia (Par. Olineri, Cuv.); but we have now cue from Brazil, and 

 some others from India. 



In the terrestrial Pulmonea with a perfect and exterior shell, the margin of its aperture is in general 

 thickened and reverted in tlie adult. 



Linnaius referred to his genus 



Heltx, — 



Every S|ieeies in wliieh the aperture of the shell (somenliat encroached upon by the projection of the 



penultimate whorl) assumes a crescent-like figure. 



When this lunated aperture is wider than it is deep, the shells belong to Helix, Brug. & Lam. In some, the 

 shell is globular. Everybody knows the edible Snail (Hel. pomatia, Linn.), common in gardens and vineyards, 

 and esteemed as a delicacy in some departments ; and the common Snail (lid. ncmoralis, Linn.), remarkable for 

 the vividness and variety of its colours, and very ^ ___^ 



hurtful to garden stulfs in wet seasons. There is 

 no one who has not heard of the curious expeii 

 ments, showing to what e.vtcnt they can reprodu. e , j 

 amputated parts. if I G( 



Other species have a depressed shell, or one with 

 a flattened spire ; and we ought not to pass over 

 without notice such as have interiorly pi-ojecting 

 ribs, nor those in which the last whorl is abruptly 

 turnedupintheadult [so that the aperture appear, p,^ l,n _\„a,toma t d « 



in the same plane as the spire], and then assuiu.s 

 an irregular plicated form,— hence denominated .i//r/.s7o»mt liy Lamarck. 



The \ilriim Drap. {Helico-Limax^ Feruss.), are Helices with an extremely thin subspiral shell, without an nm- 

 bilicus, and with an ample aperture, whose margin is sharp and even. The body of the Snail is too large to be 

 drawn w ithin the shell. The cloak has a double edge ; and the superior fold, which is divided into several lobes, 

 may be made to overlap the shell so as to clean and polish it. The European species live in moist situations, and 

 are very small •, but there are some of large size in warm climates. 



1 Uuuhiirian ; tuid the i'croni- the reflected outer li|), and tlie teeth in the ti|ierture. Until then 



t" 

 H-,lic 



I tlte 0:^d 



,ot ditlcrciit.— Ei>. 



whicli diatinnuiahea th' 



able alteration in the habit and 

 it, at tile time of its arrival at i 



enus from all the other 



raordinnry, that it appears to us to be 



inasmuch as it evidences a consider- 



eeonoiny of the animal which produces 



Is last period of growth, when it forma 



