212 



Bulletin 39 



384 



ORDER TELEODESMACEA 

 Genus CRASSATELL ITES, Kruger 



Crassatellites Reevei Gabb Plate 20, figure 4 



Crassatella antillarum Reeve ? C. Reevei Gabb 1873, Trans. Amer. 



Phil. Soc. vol. 15, p. 252. 

 Crassatellites reevei Brown and Pilsbry, 1913, Proc. Acad. Nat. Sci. 



Phila., vol. 64, p. 515, pi. 23, fig. 5. 



The Crassatellites Reevei Gabb is not an uncommon fossil 

 in the Gatun beds of western Panama and Costa Rica. Our 

 specimens agree quite closely with Brown and Pilsbry' s figure of 

 the single right valve collected by Gabb in the Miocene of Santo 

 Domingo. Young and full-grown specimens show a strong 

 posterior angulation which extends from the beak to the poster- 

 ior ventral extremity. The posterior end is obliqueh^- truncated 

 but less so in young shells. The surface sculpture consists of 

 even, concentric costse which on the slightly flattened umbos are 

 a little wider apart as in the Crassatellites of the section Scam- 

 bula Conrad. In this later character, our shells disagree with 

 Brown and Pilsbry' s redescription of Gabb's type specimen, in 

 which the sculpture is said to extend without any irregularity 

 upon the rather flattened umbos. 



The C. mediamericanus Brown and Pilsbry from Sapote, 

 Costa Rica is an earlier shell and is higher, less obliquely trun- 

 cated behind, more coarseh^ sculptured and lacks the posterior 

 angulation. In these characters except the lack of the posterior- 

 umbonal angulation it is like the young shells of Reevei. 



Length 55, height 36.5, semi-diameter 10.5 mm. 



50 35 diameter 21 mm, 



58 42 semi-diameter 14 mm. 



