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.) 



AURICULIDiE. 



LIMN.EAD.E. 



1. 2. Carychium minimum. 



3. Acme fusca. 



4. Conovulus denticulatus. 

 6. 7. Limnzeus auricularis. 



8. Ancylus fluviatilis. 



9. Physa fontinalis. 



10. Planorbis albus. 



L 2 



