412 On the Anaioiny of 



Organs of Nutrition. The mouth, as in the genera 

 Limax and Helix, consists of an ovoidal, hollow, muscular 

 organ. On its inner and upper surface, near its orifice, it is 

 provided with a horny beak, concave on its cutting edge, and 

 slightly denticulated. The tongue is a firm, apparently carti- 

 laginous organ, which, when retracted, occupies the lower 

 portion of the cavity of the mouth, also forming a process 

 which projects from its posterior face (^fig. 3, h.) The upper 

 surface of the tongue is deeply concave, and its lower convex, 

 SO that it has somewhat the form of a gouge, and it is covered 

 by a cuticular membrane, which is easily detached from the 

 body of the organ. When this cuticular covering is examined 

 under a powerful microscope, its entire surface is found to be 

 covered v/ith an immense number of minute teeth, arranged 

 in a transverse-linear series, and having a form more or less 

 conical. These on the median line (fig. 4, a,) are readily 

 distinguished from the lateral teeth, by their sj-njmetrical form, 

 and by being smaller than those nearest to them on either 

 side. The lateral teeth (fig. 4, h h and c c.) are all more or 

 less inclined towards the axis of the tongue. Those near the 

 median line, have an obtusely conical form, and at the apex 

 are surmounted by a sharper conical point. As they recede 

 from the centre, this point disappears, and the teeth become 

 regular cones, and at the same time gradually diminish in 

 size, the extreme lateral ones being reduced to minute 

 papillae, (fig. 4, cc.) The mouth is protruded and retracted 

 by two sets of muscular fibres acting in opposite directions, 

 and attached to the anterior and posterior part of the foot. 



The ceso2)hagus opens into the mouth on its upper surface, 

 (fig. 3, c,) and on each side of it are the terminations of the 

 ducts of the salivary glands. These last are two in number, 

 one on each side of the oesophagus, of an irregular flattened 

 oval form, lobulated, each discharging its secretion into the 

 mouth by a single tortuous duct, (fig. 2, h,) which passes 

 through tlie ring formed by the union of the oesophageal 

 ganglia. The oesophagus, having passed through the same 

 ring, terminates posteriorly, (fig. 2, c.) in a thin membranous 

 stomach. This last is of a nearly cylindrical form, gradually 



