CLASS GASTEROPODA: OKDER PULMONIFEKA. 347 

 Mg. m. 



MelicidOR, Land SnailB. 



the simplest form of lung — a mere cavity, with an orifice at 

 the right side of the neck which the animal can open or 

 close at will. They are herbivorous, and often very destruc- 

 tive to grain fields and fruit trees. 



mg. ms. 



Umax anUquorvm, Great Gray Slug, Europe. 



