DESCEirilONS OF SPECIES. 



77 



middle of the base. Septa 24 to 36 in number. Columella with a papillate 

 upper surface. 



«■ The base of this specimen is 5 mm. wide, exceptionally broad. 



Localities. — Claibonie, Alabama, and White's marl bed, Mom-oe County, 

 Alabama. 



Geologic occurrence. — Upper Clalbome. 



This si^ecies can usually be separated from P. stokesi by its more 

 elongate form, but that character will not hold always. The following 

 thi-ee distinctions, I believe, are of constant value: (1) the surface of P. stokesi 

 is rougher than that of P. goldfussi; (2) the intercotal furrows of P. stokesi 

 are deeper and wider than in P. goldfussi ; (3) ; the number of the costse in 

 P. stokesi never exceeds 24, while there may^ be more in P. goldfussi. I 

 carefully examined 360 specimens of P. stokesi to ascertain whether the 

 number of the costse was constant. The young specimens of these two 

 species resemble one another very closely, indicating their near relationship. 



Platytrochus claibobnensis de Gregorio. 



PI. Y, flgs. to 12. 



1890. Platyirocltus claibornensis de Gregorio. Mon. de la Fauiie eocenique de I'Ala., 

 p. 255, pi. xlv, figs. 21-22. 



Original description : 



Plat, cuneatus, compressns, subflabellatus; calice elliptico; septis 44, paulo irregu- 

 laris; columella ficta, irregulari, palis etformata; costis augnstis, coufluentibus, sub- 

 granulosis, paulo sinuosis. Haec species diflert a duabus praecedeiitibns propter 

 costas et septa multo magis numerosa, angusta, et minus regulares. Multo magis 

 rara est quam iis. 



Translation : 



Plat, cuneate, compressea, subflabellate ; with elliptical calice; 44 septa, slightly 

 irregular; columella false, irregular, formed of the i)ali; costa' narrow, confluent, 

 subgranular, slightly sinuous. This species differs from the two preceding on account 

 of its much more numerous, narrow, and less regular costie and septa. Much rarer 

 than they. 



