CLASS GASTEROPODA: ORDER PULMONIFERA. 24? 



Fig. It2k. 



Heliclace, Land Snails. 



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. 



Limax antiguorum, Great Gray Slug, Europe. 



