ORTMANN I TERTIARY INVERTEBRATES. 1 67 



99. CALLIOSTOMA SANTACRUZENSE Cossmann. 



PI. XXXI, Fig. 5-. 



1899 C. s. Cossmann, in : Journ. Conchyliol., p. 10 (of sep. cop.), pi. 10, f. 13. 



Shell conical, higher than broad, not umbilicated. Whorls slightly 

 convex, suture shallow. Last whorl angulated, with a keel on the angu- 

 lation. Above this keel, which is wholly exposed on the upper whorls, 

 there are 2 to 3 other revolving keels, which are remote from each other, 

 the uppermost close to the suture. They are crossed by oblique longi- 

 tudinal ribs, which form, at the intersection with the revolving ribs, small 

 tubercles or conical granulations. These longitudinal ribs are fairly 

 remote from each other in the upper whorls, but more crowded near the 

 mouth of the shell, resembling there lines of growth. Base of shell 

 oblique, a little convex, with 6 spiral ribs, the outermost a little more 

 distant from the peripheral keel than from the rest. These ribs of the 

 base are crossed by lines of growth (or ribs) in the same way as those of 

 the upper part of the whorls, and are also granulated at the points of 

 intersection. 



Height, 9 mm ; diameter, 7 mm. 



Remarks: Our specimens differ a little from the original description. 

 Cossmann calls the whorls convex, but they are very slightly so (also in 

 Cossmann's figure 1 ). Further, Cossmann gives 4 spiral ribs on the upper 

 whorls, with a finer one intercalated on the last whorl. In our largest 

 individual, although a little larger than Cossmann's, I can distinguish 4 

 ribs only near the mouth, with no traces of intermediate ones, and the 

 upper whorls show only three ribs. 



But since the general character of sculpture : revolving ribs, crossed by 

 longitudinal ones, with granules at the points of intersection, is well 

 exhibited in our specimens, I have no doubt that they belong to Coss- 

 mann's species. 



Record of specimens : Mouth of Santa Cruz River, 4 sp. 



Distribution: Jegua quemada, Suprapatagonian beds (Cossm.). 



1 Cossmann's figures do not help materially in the identification of the species ; they give a 

 good representation of the external form and dimensions, but in most cases the details of sculpture, 

 etc., are obscure. The fault lies with method of reproduction. 



