10 



PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



opening of the ureter into the mantle-cavity is therefore just above 

 the front end of the kidney, instead of near the mantle-edge. 

 (Compare text-fig. Sd, which shows the condition in Pyramidula, 

 Patulastra, Vallonia, and Acantkinula lamellata, with text-fig. 3e, 

 which depicts a section through the roof of the mantle-cavity in 

 A. aculeata.) Thus we might perhaps say that A. aculeata has a 

 primary ureter running forwards leading into a secondary ureter 

 running backwards, which is exactly the opposite arrangement 

 to that found in sigmurethrous forms like Goniodiscus rotundatus, 

 where the primary ureter runs backwards and the secondary ureter 

 runs forwards. 



3 c. 9* Totun.Ao.tuLS 



Figs. 3a-e. — Excretory organs of Patulastra, Vallonia, Acanthinula, and 

 Goniodiscus. Figs. 3a, 36, and 3c show the kidney, ureter, and other 

 pallial organs, as seen from the outside, after the removal of the shell. 

 Figs. 3d and 3e depict transverse sections of the roof of the mantle-cavity 

 in front of the kidney, showing the ureter in section on the right and the 

 rectum on the left. 



The evidence of the excretory system, therefore, shows conclusively 

 that none of the genera Pyramidula, Patulastra, Vallonia, and 

 Acanthinula should be placed in or near the Endodontidae or the 

 Helicidse, as they all belong to the Orthurethra. Indeed, it was 

 apparently on these grounds alone that Pilsbry in 1900 suggested 

 removing Vallonia from the Helicidae and placing it in the 

 Orthurethra in a new family.^ For while very little has hitherto 



' Loc. cit. 



