230 PROCEEDINGS OF THE ACADEMY OF [May^ 



Now AthJeta rarispina certainly has generic affinity with both Con- 

 rad's Athleta tuomeyi and Lamarck's Voluta spinosa. When we com- 

 pare Lamarck's Voluta spinosa and Conrad's Voluta petrosa, no differ- 

 ences M^hich can be regarded as other than specific are observed. We 

 have therefore at least four species of Athleta, two American and two 

 European. The two American are connected by every gradation of 

 intermediate and cannot be considered as specifically distinct. The 

 European forms are separate species.^ In spite, therefore, of minor 

 morphologic differences, and of discrepancies in the time range and in 

 the geographical distribution, we must regard these forms as belonging 

 to one generic group and apply the name Athleta to them all. Athleta 

 petrosa would then include both Voluta petrosa and Athleta tuomeyi; 

 the value of the designation tuomeyi should, however, in no case be 

 more than subspecific. 



The assemblages which may be grouped under the specific name 

 Athleta petrosa are widely distributed in our Gulf Eocene. The race 

 from any particular locality or bed usually differs from other races, but 

 nevertheless all of them possess so many characters in common that 

 further specific division would be inadvisable. Every individual 

 gradation and not a few racial gradations may be found to connect the 

 normal Athleta petrosa with the abnormal Athleta petrosa tuomeyi. As 

 far as the author knows, it is only at two localities that we find forms 

 associated with Athleta petrosa which, though closely related, must be 

 considered as distinct species.^ The cases in question are at Claiborne,. 

 Alabama, where the closely related associate species is Athleta sayana, 

 and at St. Maurice, Louisiana, where the closely related associate is here 

 designated as the new species Athleta clayi. 



The races of Athleta petrosa and their allies from the Alabama- 

 Mississippi region have been considered in a previous paper. ^ In 

 their case, thanks to the work of Prof. Eugene A. Smith and Mr. Law- 

 rence C. Johnson,^ it is possible to arrange the races in chronologic 

 order. In the present study the races discussed are mostly from the 

 Eocene beds west of the Mississippi River, and unfortunately the 



° Dr. Dall {Trans. Wag. Inst., Vol. 3, p. 75) says: "In America, however, the 

 deposition of calkis never became normal and regular, though in Europe .4. 

 rarispina and A. ficulina Lam. exhibit a normal. Cassis-like expansion around the 

 aperture of what, without it, is a typical Volutilithes." At this time Dr. Dall 

 regarded Voluta spinosa as the type of Vobitilithes. 



' Volutilithes precursor oi Dall and Volutilithes dallioi Harris.though in the same 

 genus with Athleta petrosa, are not very nearly related to it. 



*"Ph}4ogeny of the Races of Volutilithes petrosus," Proc. Acad. Nat. Sci. 

 Phila., May, 1906, p. .52. 



* Bull. 43, U. S. G. S., "Tertiary and Cretaceous Starta of the Tuscaloosa, 

 Tombigbee, and Alabama Rivers," Eugene A. Smith and Lawrence C. Johnson. 



