40 



BULtMEa-»-PUPA. 



winter, they retire into some hole, draw themselves into their 

 shell, shutting up the mouth with a calcareous matter, secreted 

 by the edge of the mantle, and remain torpid until spring. — 

 Very curious, and frequently repeated experiments, have proved 

 that not only do wounds inflicted on these animals readily heal, 

 but that considerable portions of the body, after being removed, 

 can be renewed. The eyes, the tentacles, and even the head of 

 snails have been known to be entirely renewed in this way. A 

 very great number of species of snails are known,- they are found 

 in all parts of the world. 



16. We give the name of Vitrina to snails 

 the shell of which is very thin, flattened and un- 

 provided with a thickened lip, and too small to 

 enclose the body entirely^ some small species 

 are found in Europe. The BvhuiEs^—Bulimys 

 {Jig. 23) — have an elongated shell, the open- 

 ing higher than wide, furnished with a thicken- 

 ed lip, and without notches. A small species 

 which is found in France, is re- 

 markable for the singular habit of 

 successively breaking the whorls of 

 the apex of the shell. There is a 

 large species in Brazil which is 

 eaten as a delicacy. Other mollusks of the same 

 tribe, the genus Pupa, have an ellipsoid, or even 

 almost cylindrical shell, with the opening higher 

 than wide, furnished with a thickened, notched, and 

 generally dentate lip (Jig. 24) : they are of small 

 size, and live in humid places, among moss, &c. 

 Shells of the genus Chondrus also 

 have a notched and dentate lip; but 

 their form is more ovoid. 



17. The genus of Clausilia is composed of small 

 mollusks which live in moss, at the roots of trees, and 

 have a shell similar to that of the Pupa, but much 

 more slender and pointed {fig' 25). 



18. The Ambrettes — Succinea — differ from all 

 the preceding in the absence of a thickened lip around 

 the opening of the shell, which is oval, and too small 



Fig. 23. 



BULIMUS. 



Fig. 24. 



PUPA. 



16. What is the Vitrina? What are the characters of the genus Bull- 

 mus ? How is the ge.aus Pupa distinguished ? 



17. Of what is the genus Clausilia composed ? 



18. What are the distinguishing marks of the Ambrettes ? Where are 

 they found ? 



