142 PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 



apex is, in V. navidadis, distinctly more anterior, and the sculpture seems 

 to be different. 



According to v. Ihering, this species is closely allied to the living species 

 V. exalbida Ch. from S. America. 



Gen. MERETRIX Lam. 

 68. MERETRIX (?) PSEUDOCRASSA (Ortmann). 



PI. XXIX, Fig. i"> 6 . 



1899 Cytherea ps. Ortmann, in: Amer. Journ. Sci., v. 8, p. 429. 



Shell very thick and solid, very convex. Outline almost circular, pos- 

 terior end rounded. Apex at two-sevenths of the length. Lunula and 

 area indistinct, nymphs deeply immersed. Exterior surface concentrically 

 striated, but the adhering matrix obscures the details of sculpture. Ven- 

 tral margin of shell not crenulated. Hinge with two strongly developed 

 teeth, and a smaller anterior one. Posterior tooth distinctly divided by 

 a groove, the middle one also divided on upper side. 



Length, 62 mm; height, 60 mm; diameter, 25 (x 2) mm. 



Remarks: I am unable to decide whether this species belongs really to 

 Meretrix or not. The division of the posterior hinge teeth is in favor of 

 this view, but I cannot make out whether there was a fourth (lunular) 

 tooth ; we have only the right valve, and that part of it, where we should 

 look for the groove that receives this tooth, is broken out. Perhaps it 

 would be better to leave this species with Venus. 



Record of specimens : Punta Arenas, horizon III (upper Magellanian); 

 i right valve. 



Affinities: I have compared this species with the Pliocene V. crassa 

 Phil., and the Cretaceous K alta Phil., both from Chili. 



69. MERETRIX IHERINGI Cossmann. 



PI. XXVIII, Fig. 5"' 6 . 



1897 Cytherea splendida v. Ihering, in: Rev. Mus. Paul., v. 2, p. 255, pi. 

 6, f. 42 (non C. splendida Merian). 



