134 
PATAGONIAN EXPEDITIONS : PAL/EONTOLOGY. 
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. puelchum : 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, 1 sp. ; Las Salinas, 
1 sp. ; Arroyo Gio, 1 cast ; Lake Pueyrredon, base of tertiary, 1 1 sp. 
Distribution : Santa Cruz (Phil.). 
Affinities: A closely allied species is C. sphceridium Phil, from Lebu 
(Navidad beds), but in the latter species the ribs are finer and more 
numerous. 
Gen. AMATHUSIA Phil. 
60. Amathusia angueata Philippi. 
PI. XXVII, Fig. 9 “’ b . 
1887 an §- Philippi, Tert. & Quart. Verst. Chiles, p. 135, pi. 23, f. 1, 
pk 25, f. 1. 
1897 A. ang. 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 f 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 Cardiidce. Philippi 
points out the resemblance of the hinge to that of Cardium , but relying 
on the external form of the shell he prefers to place it with Venus. V. 
Ihering (1899, p. 38) believes that Amathusia is related to Glycimeris 
(Panopeea), but I cannot see on what grounds. Indeed, there are no 
characters at all, which would warrant the position of this genus with 
