ORTMANN : TERTIARY INVERTEBRATES. 173 



by 2 to 3 sharp revolving threads. Similar threads or keels (4 to 5) are 

 on the second rib, and a number of very fine, but distinct striae are on 

 the peripheral angulation. Intervals between the ribs deep, with indis- 

 tinct revolving striae. Base of shell with about 9 revolving keels, which 

 are strong and distinctly crenulated near the umbilicus, becoming finer 

 toward the periphery. Umbilicus deep, of medium size. 



Height, 12 mm; diameter, 15 mm. 



Remarks: I am not quite satisfied that my identification of this species 

 is correct. Cossmann mentions crenulations on the inferior part of the 

 whorls, while my individuals show them only in the upper part : this dis- 

 crepancy is not cleared up by Cossmann's figure, which shows no crenu- 

 lations at all. In all other respects our individuals agree with Cossmann's 

 figure and description, but it is to be remarked that the figure represents 

 an individual that is apparently considerably worn. In our figured speci- 

 men the surface ornaments are in a beautiful state of preservation, and all 

 of them are more distinct and more pronounced than in Cossmann's figure. 



In another of our specimens the upper revolving rib does not show any 

 finer keels, but is bipartite, the lower division being a little narrower and 

 showing also traces of crenulations. The third individual is very small, 

 while the other two are considerably larger than the measurements given 

 by Cossmann. 



Record of specimens : Mouth of Santa Cruz River, 3 sp. 



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



Fam. PYRAMIDELLID^ Gr. 

 Gen. ODONTOSTOMIA Jeffr. 



105. ODONTOSTOMIA SUTURALIS (v. Ihering). 



PI. XXXIII, Fig. 7"' 6 . 



1897 Odostomia sut. v. Ihering, in: Rev. Mus. Paul., v. 2, p. 275, textf. 10. 



1899 Odontostomia synarthrota Cossmann, in: Journ. Conchyliol., p. 12, 

 (of sep. cop.), pi. n, f. 4. 



1900 Odontostomia sut. Ortmann, in: Amer. Journ. Sci., v. 10, p. 380. 

 Shell pyramidal, smooth; whorls 7 (9 according to v. Ihering), flat, 



angulated near the suture, last whorl rounded. Mouth oblong, inner lip 

 with a fold below. 



