ORTMANN : TERTIARY INVERTEBRATES. 133 



58. CARDIUM PUELCHUM Sowerby. 



PI. XXVII, Fig. 7. 



1846 C. p. Sowerby, in : Darwin, Geol. Observ. S. Amer., p. 251, pi. 2, f. 15. 

 1899 C. p. v. Ihering, in: N. Jahrb. Miner., etc., v. 2, p. 15. 



Shell subglobular, posterior end with an indistinct angulation running 

 down from the apex toward the posterior margin. Surface of shell with 

 very numerous (60-80) radiating ribs, which are about as broad as the 

 intervals. On the posterior part of the shell these ribs are a little higher 

 and sharper. In all our specimens (as in Sowerby's) the outer layer of 

 the shell is gone : only in that from Las Salinas remains of it are still 

 present; here the ribs are flat, and appear to be separated by narrow, 

 impressed lines. 



Length, 30 mm ; height, 30 mm ; diameter (double shell), 20 mm. 



Record of specimens : Mouth of Santa Cruz River, 2 double, 7 single 

 valves ; Las Salinas, i double valve ; Mt. of Observation, upper horizon, 

 i double valve ; Canon near Sierra Oveja, 2 casts: 



Distribution: Santa Cruz (Sow.), ibid., Patagonian beds (v. Ih.) 



Affinities: C. coinatnliitn Bronn (see: Speyer, 1864, p. 301, pi. 41, f. 

 10, and v. Koenen, 1868, p. 244, pi. 29, f. 1,2) from the Middle and 

 Upper Oligocene of Germany, and the Miocene of the Azores, seems to 

 be closely allied. It has the same general form, but is smaller, and the 

 radiating ribs are less strongly developed. The same type of Cardium is 

 continued from the Miocene to the Recent time in Europe by C. fragile 

 Brocchi (see: Hoernes, 1870, p. 173, pi. 30, f. 6). 



An Eocene representative of these species is C. difficile Deshayes (1860, 

 p. 572, pi. -55, f. 6, 7), but it is distinguished by the distinctly broader 

 form and more distinct posterior angulation. 



C. puelchum is clearly more closely allied to the Oligocene and Neogene 

 species mentioned. 



59. CARDIUM PISUM Philippi. 



PI. XXVII, Fig. 8. 



1887 C. p. Philippi, Tert. & Quart. Verst. Chiles, p. 179, pi. 9, f. 9. 



Shell small, ovate, subglobular, scarcely oblique. Surface with 25-30 

 radiating ribs, which are rounded and crossed by concentric lines of growth. 



