- 153 - 



Suoh a conclusion is natioral from a consideration of the charac- 

 ters of the cardinal area which is more like that of the section 

 Argina than would be expected in a Ounearca. The hinre and outline, 

 however, are not arginoid, and it is probable that adult shells 

 would have a more equilateral cardinal area. 



This is the only representative of the nujnerous races of high 

 V-- Areas that have a rather inde-Tert iary distribution in the Qarib- 

 bean ro^rion. Its cardium-li'"e form and extreme infl. ation are 

 no tevi-orthy. 



Urbina (1) has described A. chavezi from the Miocene of Su- 

 fi) . Bol. 3oc. geol. mexicane, vol. 5, iDt. 2, Top. 1?1-1?2, pi. 

 60, figs. 56-60, 62-65, 1910. 



^Ci- ------------------------------- 



luzum, 3hipas, Ve-iao ; it reaches a mxieh larger size and is less 

 roujnded, bein?' more "aroiiuced posteriorly and with a streighter 

 base. A'oparently this species is decidedly variable, a form such 

 as the one represented by fig. 63 closely resembling opthanta in 

 outline; the Oaloosahatchie A. alcina Dal 1 (2) differs in a simi- 



(2). Trans. Wagner Jree Inst. Sei., Philadelphia, vol. 5, ^t , 

 4, pp. 555-656, pi. 51, fig. 5, 7, 1898. 



lar manner. The yomig of the recent 'Jest Indian A. cher^ni t?i 



