252 Bulletin 39 424 



centric lines which are slightly lamellose on the posterior-dorsal 

 margin; interior concealed. 



Length 32, height 19, semi-diameter 2 mm. 



This species is related to the recent West Indian T. angulosa 

 Gmelin and its Pacific analogue, the T. rzibescens Hanley . The 

 fossil shell differs by its more central beaks and sharper concen- 

 tric sculpture, which is continued across the entire surface of 

 the disk. 



Gatun Stage: Hill No. j, Banana River. 



Teilina dariena Conrad Plate 26, figure 3 



Tellina dariena Conrad, 1857, Pacific R. R. Reports, vol. 5, p. 328, 

 pi. 6, fig. 53. 



Tellina semilcevis Gabb, 1861, Proc. Acad. Nat. Sci. Phila., vol. 12, p. 



567. 

 Tellina Dariena Gabb, 1881, Journ. Acad. Nat. Sci. Pnila., vol. 8, p. 



343, pl. 44 fig. 13- 

 Tellina Rowlandi Toula, 1908, Jahrb. der K-K. Geol. Reichsanstalt 



vol. 58, p. 728, pi. 28, fig. II. 

 Tellina Rowlandi Brown and Pilsbry, 191 1, Proc. Acad. Nat. Sci. 



Phila., vol. 63, p. 368. 



Conrad's figure of Tellina dariena is ver}^ poor but probably 

 represents this species, the most abundant Tellina at Gatun. 

 Conrad's figure shows a subtrigonal shell, with a produced and 

 truncated posterior extremit}^ In 1861, Gabb described Tellina 

 semileevis together with Area chitiquiensis from the Gatun beds 

 of the Chiriqui Lagoon. This species Gabb however later con- 

 sidered S3mon3nnous with the earlier Tellina dariena of Conrad. 

 Toula' s Tellina Roivla7idi is certainly identical with Gabb's 

 Tellina semilcEvis as figured by Gabb. 



Shell but slightly convex, subequilateral with the beaks sit- 

 uated a short distance posterior to the middle of the shell; anter- 

 ior and posterior dorsal slopes straight and evenly descending; 

 posterior end rounded and subtruncate, the anterior rounded ; 

 beaks low; surface striated with very fine concentric lines and 



