1 66 PATAGONIAN EXPEDITIONS I PALAEONTOLOGY. 
above this is a similar one, which is strong, but not quite as broad as the 
first one ; near the suture, on the upper part of the whorls, there is a much 
finer, but distinct keel. No granulations on the keels. The two larger 
ones broad and rounded, and, on the last whorl, near the mouth of the 
shell, bifid. All three keels separated by broad, smooth grooves, about 
as broad as the middle keel. Base of shell almost flat, with 8-10 revolv- 
ing ribs, which are flat and smooth, more crowded toward the periphery, 
a little more widely distant toward the umbilicus ; the furrows between 
them, however, are always narrower than the ribs. 
Height, 8.5 mm ; diameter, 9 mm. 
Record of specimens : Mouth of Santa Cruz River; 3 sp. 
Distribution : Jegua quemada, Suprapatagonian beds (Cossm.). 
Affinities : Cossmann says that, among the fossil species, C. audebardi 
Bast, from the Lower Miocene of Bordeaux is the most closely allied form. 
98. Calliostoma cossmanni Ortmann. 
PI. XXXI, Fig. 4 0 ' 6 . 
1900 C. e. Ortmann, in: Amer. Journ. Sci., v. 10, p. 372. 
Shell conical, higher than broad, not umbilicated. Whorls flat, the last 
one angulated, with a keel on the periphery, which is wholly exposed on 
the upper whorls, being situated close to, but above the suture. Upper 
whorls with 5 revolving keels, the lowermost (the keel of the periph- 
ery just mentioned) the strongest and almost smooth, with hardly any 
traces of granulations. The uppermost (first) and the third keels stronger 
than the 2d and 4th; the 1st, 2d, and 3d distinctly granulated, the 4th 
with finer granulations. Toward the apex of the shell, the 2d and 4th 
keels disappear, so that only three keels are present, the two upper ones 
granulated, the lower one (peripheral angulation) smooth. (Perhaps it 
was also finely granulated, but if so, the granules are worn off.) Base of 
shell hardly convex, with 6 revolving keels, which are subequal, smooth, 
narrower than the intervals. One or two of the keels, nearest to the 
periphery, appear bifid toward the mouth of the shell. 
Height, 8 mm; diameter, 6.5 mm. 
Record of specimens: Mouth of Santa Cruz River, 4 sp. 
