58 STUDIES IN GEOLOGY, No. 3 



buted over the nodose whorls. Aperture unknown. Height 

 of specimen bearing 4^ whorls, 32 ; diameter, 16 mm. 



A number of worn specimens of this Cerite were collected 

 from the Upper Zorritos formation, and one from the upper 

 part of the Variegated beds. A small group from the Varie- 

 gated at Quebrada de los Angeles may be referable to this 

 species, but they are in bad condition, and are not identifi- 

 able. The most closely related species appears to be C. rus- 

 selli Maury, 52 from the upper horizon in Santo Domingo. 

 C. grillanum differs from russelli in that the larger and 

 smaller nodes of the sculpture are reversed in position, the 

 more prominent ones being above; and there is no sub-su- 

 tural sulcus in grillanum; the prominent nodes swell out 

 beneath the suture with no interruption. 



Upper Zorritos; Variegated. Quebradas del Grillo, del 

 Toro, de los Angeles, Tijeritas, near Boca Pan. 



Genus POTAMTD^S Brongniart 

 Potamides ormei var. infraliratus n. var. 

 PLATE II Fig. n. 



Shell large and solid, the whorls closely coiled, the apical 

 angle moderate. Early whorls unknown : the complete shell 

 might have ten or twelve whorls. Whorls usually flat, some- 

 times slightly convex; the sutures ordinarily indistinct. 

 Cancellate sculpture of quadrate beads formed by the inter- 

 section of longitudinal and spiral grooves which set off 

 strap-like ribs ; the longitudinal grooves are arcuate on each 

 whorl, and are about 30 in number to the whorl ; the spiral 

 furrows set off three rows of beads, of which the anterior 

 two are subequal in width and the posterior-most is much 

 broader. Beneath the beads of the body whorl are seven or 

 eight strap-like spiral ribs which form the basal sculpture. 

 The body whorl flares at the aperture, the sculpture opening 



83 Bull. Amer. Pal., vol. 5, No. 29, p. 123, pi. 22, figs. 2, 3, 1917. 



