252 



Bulletin 39 



4«4 



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. rudescens 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. 



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



Phila., vol. 63, p. 368. 



Conrad's figure of Tellina dariena is very 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 extremity. In 1861, Gabb described Tellina 

 semilcsvis together with Area chiriquiensis from the Gatun beds 

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

 sidered synonymous with the earlier Tellina dariena of Conrad. 

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

 Tellina semilcBvis 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 



