474 



ZOOLOGY. 



physa (the helix fontinalis), which live in stagnant watn>, and 

 ascend to the surface to breathe the requisite air. Amongst 

 the gasteropodes provided with gills enclosed in a dorsal 

 cavity, may oe observed the volutes, the buccinures, the porce- 

 laines (Fig. 158), the heliotides, &c. The patellae and the 



Fig. 456. Eolis. 



pleuro-branchise (Fig. 455) carry these organs in the furrow 

 separating the foot from the mantle ; and in the doris and 

 the eolis (Fig. 456), &c., they consist in bunches and in straps 

 or leashes fixed on the dorsal aspect of the body. 



608. The mouth of the gasteropodes is surrounded by con- 



a br 



Fig. 457. Carinaria.* 



tractile lips, and sometimes armed with horny teeth occupying 

 the palate. In several other animals of this class the anterior 

 part of the gullet is very fleshy, and may be carried outwards 



* 6, mouth ; t, tentacles ; y, the ej'es ; c, stomach ; /, liver ; a, anus ; 

 c, shell ; br, gills ; p, the foot ; c, ventouse (cupping-glass-cavity air hole) 

 situated under the edge of the foot. 



