AURICULID.E. 



219 



B. THE AQUATIC FREE- AIR-BREATHING MOLLUSCA 

 have two contractile, compressed tentacles, with the 

 eyes sessile, near their base ; the head is contractile ; 

 they are not provided with any operculum. They 

 are all aquatic, and the British species are divided 

 into two families. (See p. 101.) 



AURICULID^E. 



LIMN.3EAD.E. 



10 



1. 2. Carychium minimum. 



3. Acme fiisca. 



4. Conovulus denticulatus. 

 6. 7. Limnaeus auricularis. 



8. Ancylus fluviatilis. 



9. Physa fontinalis. 



10. Planorbis albus. 



L 2 



