2 TURBID^:. 



as the representatives of families or subfamilies, 

 is still an open question. I have here adopted 

 the more enlarged signification of the term 

 family, although I might for convenience have 

 placed the few genera here described in La- 

 marck's family Peristomata, to which they cor- 

 respond. 



Mr. Swainson proposes the name Turbidse 

 for a family at the head of which he places 

 Amphibola, Schum., (Ampullacera, Quoy^ as a 

 doubtful subfamily, after leaving the Physadae, 

 to which the mollusk is allied in several im- 

 portant particulars.'* The subfamily Ampul- 

 larinae follows, including Valvata, Ampullaria 

 and Paludina; and the subfamilies Melanianse 

 and Turbinae are placed next, closing the family, 

 which is thus made to stand between the Heli- 

 cidae and Naticadae. 



The last arrangement has much to recom- 

 mend it, the principle objection to it being the 

 situation of the Helicidse before the more highly 

 organized genera Ampullaria, Melania, &c. 

 But this objection holds against every system 



* See Deshayes' Lamarck, viii. 538. 



