MANUAL OF CONCHOLOGY. 



PULMONATA. 



The subclass Pulmonata includes all mollusks breathing air. 

 They are normal gastropods, having a broad foot and usually, a 

 large spiral, inoperculate shell. Although mostly terrestrial, a 

 few aquatic and a number of fluviatile forms are here included. 

 There are no marine species, but the Auriculidae are in great 

 part inhabitants of seashores where, at high-tide, they are covered 

 by the waters. As to food, some are carnivorous, but the sub- 

 class is, as a rule, phytophagous. The teeth are numerous, 

 similar, recurved, aculeated or dentate at the extremity, with 

 broad pavimental bases. These teeth are developed many in a 

 row, upon a broad lingual ribbon ; when the rows are straight the 

 teeth are similar throughout, when curved or angulated the forms 

 of the teeth become more or less changed. There is usually a 

 single, rather conspicuous upper jaw, composed of one or of three 

 pieces never of two pieces as in the branchiferous mollusks. 



Sexes united in each individual, but the union of two individ- 

 uals required for mutual impregnation. Genital orifices some- 

 times contiguous, opening in a common cloaca, sometimes 

 distinct. 



The Pulmonata are related to phytophagous sea-snails through 

 the Cyclostomse or operculated land-snails, and the Ampullariae, 

 to the limpets through Gadinia, Siphonaria, to the nudibranchs 

 through Onchidium. 



Detailed accounts of the structure, development, habits, geo- 

 graphical and geological distribution of the Pulmonata are given 

 in the " Structural and Systematic Conchology," and need not 

 be reproduced here. 



