134 PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 



Length, 9.5 mm; height, 10.5 mm; diameter, 4.5 (x 2) mm. The 

 specimen from Las Salinas : height, 1 1 mm. 



Remarks: v. Ihering (1897, p. 251) hints that this may be only a variety 

 of C. puelclinm : but the very much smaller number of ribs does not sup- 

 port this view. Philippi says that the radiating ribs are indistinct near 

 the anterior and posterior margins: this is true in our specimen from 

 Santa Cruz, but this feature is due to the exfoliation of the upper layer 

 of the shell. In the specimens from Lake Pueyrredon the shell is partly 

 preserved, and the ribs are distinct also near the anterior and posterior 

 margins, although a little finer and less high than in the middle. 



Record of specimens: Mouth of Santa Cruz River, i sp. ; Las Salinas, 

 i sp. ; Arroyo Gio, i cast; Lake Pueyrredon, base of tertiary, 11 sp. 



Distribution : Santa Cruz (Phil.). 



'Affinities: A closely allied species is C. sphccridiuui Phil, from Lebu 

 (Navidad beds), but in the latter species the ribs are finer and more 

 numerous. 



Gen. AMATHUSIA Phil. 

 60. AMATHUSIA ANGULATA Philippi. 



PI. XXVII, Fig. 9"'. 



1887 A. ang. Philippi, Tert. & Quart. Verst. Chiles, p. 135, pi. 23, f. i, 



pi. 25, f. i. 

 1897 ^- an S- v - Ihering, in: Rev. Mus. Paul., v. 2, p. 257, textf. 2. 



Shell large, smooth, subcordate, oblique, with irregular concentric lines 

 of growth. Apex at */$ of the length of the shell. Anterior dorsal margin 

 straight, posterior first straight and horizontal, then oblique, forming with 

 the posterior margin a rostrum. 



Length, ca. 190 mm; height, ca. 150 mm. 



Remarks: There cannot be any doubt that the proper position of the 

 genus Amathusia is near Cardium, and in the family CardiicUz. Philippi 

 points out the resemblance of the hinge to that of Cardimu, but relying 

 on the external form of the shell he prefers to place it with JScnns. V. 

 Ihering (1899, p. 38) believes that AmatHusia is related to Glycinieris 

 (Panopcea], but I cannot see on what grounds. Indeed, there are no 

 characters at all, which would warrant the position of this genus with 



