303 



to render its exact determination possible. Irrespective, however, 

 of its generic placement, the specific name will remain the same, 

 as Sowerby's rivalis was listed as a Physa. 



Fred Baker (1914, p. 661) records P. sowerhyana Orb. as a 

 synonym of P. rivalis Mat. and Rack. A careful study of both 

 figures and specimens separates these forms as quite distinct and 

 demonstrates that P. sowerbyana is certainly a true Physa while P. 

 rivalis (= marmorata) , as stated above, is possibly an Aplexa. 



H. B. Baker (1930, p. 36) in a recent pubhcation on Venezuelan 

 Mollusca has treated Bulla rivalis Mat. and Rack, as an Aplexa 

 and has considered it as a member of the South American fauna. 

 The citation of Hampshire, England, as the type locaUty by these 

 authors precludes any assumption that their species was any- 

 thing else other than British. This form considered by Baker 

 is apparently Aplexa peruviana Gray. 



P. rivalis Pot. and Mich, is a synonym of Aplexa peruviana 

 Gray, the figures given by these authors being practically the 

 same. The following synonymy is given for the Peruvian 

 species : 



Aplexa peruviana Gray. 



1828 Physa peruviana Gray, Spic. Zool. pt. 1, p. 5, pi. 6, fig. 

 10. Between Lima and Callao. 



1838 Physa rivalis Pot. and Mich., Gal. des Moll., Paris, vol. 



1, pi. 22, fig. 21-22, p. 226; non B. rivalis Turton; non 

 B. rivalis Mat. and Rack.; non P. rivalis Sby. 



1839 Physa peruviensis 'Muhlfeldt', Anton, Vereichniss der 



Conchylien welche sich in der Sammlung von H. E. 



Anton befinden, Halle no. 1785. ^ 

 1845 Physa antonii Ktister, Conch. Cab., vol. 1, pi. 17, p. 11, 



pi. 2, fig. 6-8. 

 1887 Aplecta carolita Jousseaume, Bull. Soc. Zool, France, vol. 



12, p. 184, pi. 3, fig. 5. 

 1887 Aplecta martinidella Cousin, Bull. Soc. Zool. France, 



vol. 12, p. 262, pi. 3, fig. 5. {Nomen nudum, referring 



to the figure of carolita.) 



^ I have been unable to see this paper, but the same species with the name 

 changed to P. antonii is described and figured by Ktister in the Conchylien 

 Cabinet. 



