296 NEW YORK STATE MUSEUM 



Fia. 



5, 6 Profile and ventral views of a shell about one month old, 

 natural size and enlarged. 



7 Dorsal and lateral views of a shell about three months 

 old, natural size. 



8, 9 The same, x 3. 



10 Surface of the shell, x 10. 



11 The same, x 20. 



12 Transverse section of the prismatic layer of the shell, x 100. 



13 A section of a part of the peristome, x 40. 



14 A section of the peristome and a part of the shell, x 10. 



15 A section of the shell; cuticle; outer layer; median layer; 



inner layer. 



16 A section of the volutions, x 2. 



17 One volution more highly magnified, x 6. 



18 A transverse section of the peristome, x 2. 



PLATE 3 

 Fig. 



1 Dorsal view of a shell and extended animal. The smaller 



figure represents a newly hatched animal. Both figures 

 are natural size. 



2 Profile view of shell and extended animal, natural size. 



3 An animal from which the shell has been removed, show- 



ing protruding penis; 1 penis; 2 anus; S stomach; ^ ovo- 

 testis; 5 intestine; 6 digestive gland; 7 kidney; 8 pulmon- 

 ary vein. 



4 The same view as in figure 3, the volutions being partially 



uncoiled to show the position of the generative organs. 

 For explanation of the organs see plate 23, figure 9. 



5 Ventral view, the animal being retracted within the shell ; 



i, respiratory orifice. 



6 Laterobasal surface of the integumen't, x 6. 



7 A part of the integument of the dorsal part of the foot, x 6. 



