SPECIAL ANATOMY. 
203 
foot. The pulmonary chamber occupies a position on 
the outer side of the lower one to three whorls of the tur- 
binated mass. The collar apparently takes the place of 
the mantle in slugs. In all the genera it is attached 
around the base of the turbinated mass, and is perfora- 
ted on the right side by the pulmonary orifice. On the 
outer border of the latter the anal aperture is placed. 
As in slugs, the genital orifice is situated on the right 
side of the head, just posterior to the tentaculse. 
Chapter hi. — on the tegumentary covering of the 
terrestrial gasteropoda. 
Besides a testa capable of enclosing the whole body, 
which most of the terrestrial Gasteropoda possess, they 
have a thick envelop, composed of mucous and muscular 
membrane. The exterior, highly irritable and contractile 
investment consists of an actively secreting mucous mem- 
brane, (Figs. A, B, C, 1) with a substratum of interlaced 
muscular fibres (2). In the naked genera it is pretty 
Figure A. 
Fig. A is a diagram representing the disposition of the coverings of 
l he body in Limax and Arioii, I. mucous lamina ; 2. muscular substratum ; 
3. muscular peritoneum ; 4. visceral cavity ; 0. rudimentary testa ; 6. ] ul- 
monary chamber. 
