148 PATAGONIAN EXPEDITIONS! PALAEONTOLOGY. 



length. Anterior end rounded, posterior indistinctly biangulate. Pallial 

 sinus linguiform, reaching hardly to the middle of the shell. 



Length, 28.5 mm; height, 20 mm; another: length, 27111111; height, i8mm. 



Remarks: Our casts of the left valve agree completely with v. Ihering's 

 figure, and one of them shows also the pallial sinus. The external cast 

 of a right valve, however, is convex, and perhaps it does not belong here. 

 In the largest individual, near the ventral margin, faint indications of 

 radiating striae are seen. 



Of this species, so far only the cast is known. 



Record of specimens : Shell Gap, Rio Chico, upper horizon, 2 internal 

 casts of left valve, i external cast of right valve. 



Distribution: Santa Cruz, Patagonian formation (v. Ih.). 



75. TELLINA JEGUAENSIS v. Ihering. 



PI. XXVIII, Fig. 8. 

 1897 T. j. v. Ihering, in: Rev. Mus. Paul., v. 2, p. 260, pi. 5, f. 33. 



Shell thin, subpyriform, smooth. Anterior end longer, rounded, pos- 

 terior narrowed and acuminate, near the posterior dorsal margin a radi- 

 ating angulation. 



Length, 20 mm; height, 14 mm (according to v. Ihering: length, 25 

 mm; height, 16 mm; diameter, 4 mm). 



Remarks: Our individuals from Santa Cruz are smaller, but otherwise 

 agree well with v. Ihering's figure. The specimens from Arroyo Gio are 

 a little higher comparatively, and the anterior end is less elongated. 



Record of specimens : Mouth of Santa Cruz River, 2 valves ; Arroyo 

 Gio, 5 casts. 



Distribution: Jegua quemada, Suprapatagonian beds (v. Ih.). 



Affinities: T. promancana Phil. (1887, p. 141, pi. 26, f. 9) from Navi- 

 dad comes near this species, but it is equilateral (anterior end not longer 

 than posterior), and higher (L., 26; H., 19; rel. = 1.26: i). Our indi- 

 viduals from Arroyo Gio are intermediate in form between T. promancana 

 and jegnacnsis: rel. = 1.42:1, while in the typical form, according to v. 

 Ihering, the rel. is = 1.56: i. The anterior end in the Arroyo Gio speci- 

 mens is less elongated than in the typical form, thus approaching 7\ 

 promaucana in this character also. 



T. capillifera Conr. (see: Whitfield, 1894, p. 76, pi. 14, f. 8-10) from 

 the Miocene of New Jersey is hardly distinguishable from this species. 



