Paleontology Zorritos Formation 59 



out in fan-shape, and the sutural margin ascending to cover 

 part of the preceding whorl. The aperture is large, pointed 

 oval in shape, with the outer lip strong and thickened and 

 the callus heavy. The posterior notch is distinct ; the anter- 

 ior canal is truncate, sharp. Height of fragment bearing 

 the low-er four whorls, 37 mm. ; maximum diameter at base, 

 24 mm. ; at 4th whorl, 10 mm. A longer fragment, bearing 

 5 whorls, but lacking the outer lip of the aperture, is 41 

 mm. in height, and probably had a maximum diameter of 

 27 mm. 



Several specimens of this Potamides, from both the Upper 

 Zorritos and the Lower Zorritos formations, are very close 

 to P. ortnei Maury ,'^ from the Middle Oligocene of Santo 

 Domingo, and might be united with it in a loose regard for 

 specific limitations, but the sculpture varies constantly from 

 that of P. ornvei, and the Zorritos specimens are distinctly 

 larger and heavier. The upper set of quadrate beads on the 

 whorls of infraliratiis is proportionally larger than in ormei, 

 and there appear to be more spiral ribs on the base. Maury's 

 figure is not clear, and her description lacks mention of 

 many important points, but there are apparently about five 

 lirae beneath the beads on the body whorl of ormei, instead 

 of seven or eight, and the number of longitudinal grooves 

 to the whorl seems to be less than in infraliratus. These 

 diflferences are very constant in the specimens of the Hop- 

 kins collection. 



Lower and Upper Zorritos. Quebradas del Grillo, de I03 

 Angeles and Heath. 



Family TURRITELLIDAE 



Genus Turritella Lamarck 



Tiirritella altilira Conrad 



Pl.\te II — Fig. 12. 



Ickm., p. 126, pi. 22, fig. 8. 



