4 PULMONATA. 



B. Head, eye-peduncles and tentacles simply contractile. 



6. Veronicellid^. Body elongate. Teeth numerous, four- 



sided, close on the lingual membrane. 



7. Onchidiad^e. Body ovate. Teeth numerous, four-sided, 



close on the lingual membrane *. 



II. LIMNOPHILA. Eyes sessile. Tentacles two, subcylindrical 

 or flattened, simply contractile. Operculum none. 



8. AuRicuLiD^. Eyes on the nape at the inner side of the 

 base of the subcvlindrical tentacles. Teeth like Helicidw 

 (fig. 3). 



Fig. 3. — Teeth of Auricula. 



9. LvMNEAUiE. Eyes on the hinder side of the base of the flat- 

 tened or filiform tentacles. Teeth like Helicidce. 



III. THALASSOPHILA. Eyes sessile, on the front part of the 

 frontal disk formed by the expanded tentacles. Head pro- 

 duced. Lingual membrane very broad. 



10, SiPHONARiADiE. Shell conic. Operculum none. Teeth 

 like Helicidce (fig. 4). 



Fig. 4. — Teeth of Siphonaria. 





* The teeth described as those of Peronia Mauritiana, in the Ann. 

 of Nat. Hist., Nov. 1853, were those of Tenfacellus. See Ann. and 

 Mag. N. H. Jan. 1854. 



