CALIFORNIA ACADEMY OF SCIENCES. 255 



"Arionta" p. 157. Here Mr. Binney, himself, states that 

 "Townsendiana has quite different genitalia from Arionta," 

 which with its shell indicates its more correct reference to 

 Mesodon. 



He also says that the genitalia of H. Mormonum differ es- 

 sentially "being more nearly allied to that of Aglaia fidelis 

 and infumataj" So if the latter are not Arioutae, neither is 

 Mormonum, or Hillebrandi, which is as much a variety of it 

 as the circumcincta Stearns (p. 158). But Aglaia will have 

 to be dropped as the generic name, being twice pre-occupied. 



The figures B, C and G, on Plate IV, represent some of 

 the intermediate forms connecting jidelis with in/umaia and 

 with Mormonum. 



