Gastropoda. 



2.-> 



(Crepidula) and the ' Cup-and-saucer Limpets' (Crucibulum). 

 They rarely crawl about, but remain attached to rocks, stones. 

 or other shells, sometimes forming a shelly plate under the foot 

 by which they become fixed to the spot where they have taken 

 up their abode. The American Crepidula fornicata has established 



Fin. 1G. 



A mp ullar ia ca nal ic ulata. 

 Fig. 17. 



N 





C 7 



>«^W 



e 





The Tiger Cowry (Cypraea tigris). (From the Indo-Paeific Ocean.) 

 a. the shell ; b. the mantle ; c. foot ; d. siphon ; e. proboscis ; /. tentacles ; 



g. eyes. 



itself on the coasts of England to the great disturbance of Oyster 

 culture. The Slipper- Limpet multiplies very rapidly and encrusts 

 the Oyster-beds, intercepting the normal food of the Oysters. 

 These animals settle down in clusters one on top of another 

 (Case 31). In the individuals composing such strings there is 

 a change of sex, the oldest (at the bottom) being females, the 

 intermediate ones hermaphrodite, and the youngest (at the top) 

 males. 



