Ortmann — Invertebrate Fossils from Patagonia. 373 



ones granulated, the lower one smooth. Base of shell hardly 

 convex, with six revolving keels, which are subequal, smooth, 

 and narrower than the intervals. Height, 8 mm ; diameter, 

 6*5 mm . 



Santa Cruz. 



18. Calliostoma garretti sp. nov. Shell conical, as high as 

 broad, not umbilicated. Eight whorls, which are very slightly 

 convex, suture shallow. Last whorl very bluntly angulated at 

 the periphery, without a distinct keel. Surface of whorls, 

 above the periphery, covered with numerous fine, revolving 

 threads : there are, on the third whorl, about 7 of them, 

 increasing to about 17 on the last. The number of the threads 

 increases by intercalation, the new keels being at first smooth, 

 but soon they equal the others, and become, like the latter, 

 finely, but distinctly granulated. These granulations, how- 

 ever, are developed only in the upper three quarters of the 

 whorl, the lower four or five threads remain smooth. The 

 threads continue over the periphery to the base of the shell, 

 which is slightly convex ; their number, on the base, is about 

 24, and they are smooth, resembling in all other respects those 

 of the upper part of the whorls. Height and diameter 17 mm . 



Santa Cruz. 



19. Calliostoma iheringi sp. nov. Shell conical, broader 

 than high, umbilicated. Six whorls, which are sharply angu- 

 lated, one angulation being formed by a sharp revolving keel 

 in the upper part of the whorls, a second one — exposed only 

 on the last whorl — formed by a peripheral keel. Suture dis- 

 tinct. Upper part of whorls (above upper keel) oblique, fiat, 

 with 5-6 revolving threads, which are slightly granulated ; lower 

 part vertical, slightly concave on the last whorl, with 6-7 fine, 

 smooth threads. Base of shell slightly convex, depressed toward 

 the umbilicus, which is moderately large. About 18 revolving 

 threads on the base, which are smooth, more crowded and 

 finer toward the periphery, a little stronger near the umbilicus. 

 Height, 9-5 mm ; diameter,' 12 mm . 



Santa Cruz. 



20. Crucibiilum dubium spec. nov. Cast suborbicular, 

 depressed-conical. Apex central. On one side is the impres- 

 sion of the internal cup-shaped lamina, which was attached to 

 the inner wall of the shell. No further characteristics can be 

 given, since only a single cast is represented in our collection. 



Arroyo Gio. 



21. Sigapatella americana sp. nov. Shell suborbicular or 

 subelliptic, depressed. Apex distinctly excentric. Surface 

 with irregular, concentric, slightly lamellate stirse, crossed by 

 very fine radial rugosities. Internal diaphragma spiral, colu- 



