414 



MOLLUSC A : GASTEROPODA. 



FIG. 588. 



latitliina fragilii, Lamarck. Atlantic. 



a, raft; 6, egg capsules; c, gills; d, tentacles and eye-stalks. 

 FIG. 589. FIG. 590. FIG. 591. 



a er/uestris, L. 

 Philippines. 



FIG. 592. 



Patella tcsturlinalis, Miiller. 

 New England. 



Fissurella Lisleri. 

 West Indies. 



FIG. 593. 



Crepidula fornicata, Say. 

 New Englaud. 



Chiton ruber, L. New England. 

 FIG. 594. 



Dentalium dentalis, L. 

 Atlantic. 



2. The PULMONIFERA, as already indicated, on page 406, 

 are the Land-Snails and other gasteropocls which are pro- 

 vided with a lung-like organ, formed for breathing air. 

 This organ is a cavity or chamber lined with a net-work 

 of respiratory vessels. The orifice leading to this lung- 

 like organ is small and valve-like ; this prevents the too 

 rapid drying in the land species, and prevents the ingress 

 of water in the aquatic species. Unlike the Sea-Snails, 

 the sexes are united in each individual. 



