88 STUDIES IN GEOLOGY, No. 3 



outer margin. There is a wedge-shaped portion of the 

 upper lip projecting over the callus. The callus is sharply 

 emarginated below, at about the anterior third, the outer 

 margin making a right-angled indentation, and the callus 

 continuing at about half its upper width ; it extends below 

 into a folding-over of the lower inner peristome. The um- 

 bilicus is situated at the right-angled emargination of the 

 callus. The nuclear whorls are smooth; the later whorls 

 sculptured by lines of growth. Dimensions : Large mature 

 shell, Height, 55 ; Diameter, 43.5 mm. Medium-sized shell, 

 Height, 31.5; Diameter, 28.5 mm. Young shell, Height, 18; 

 Diameter, 14 mm. Very young shell, Height, 7.5 ; Diameter, 

 6.5 mm. 



This species is very abundant. It is characterized by the 

 sub-plane sides of the whorls, and the peculiar, wedge-shaped 

 callus. It differs very slightly from Polinices stanislas- 

 meunieri Maury, 75 from the Middle Miocene of Santo Do- 

 mingo; the spire of subangulata is lower, and the apical 

 angle hence wider; the whorls are flattened on the sides, 

 and not smoothly rounded; and the callus is wedge-shaped, 

 the margins converging anteriorly, whereas that of stanislas- 

 meunieri has parallel margins. The chief difference lies in 

 the different apical angle. 



Lower Zorritos; Variegated. Ridge between Quebradas 

 Heath and Charan, Quebrada Tusillal, south of Ouebrada 

 Pantheon. 



Polynices porcana n. sp. 

 PLATE IV Fig. 9. 



Shell fairly large, heavy, the spire low and the apical 

 angle somewhat broad. Whorls about five, well rounded and 

 smooth excepting perceptible growth- wrinkles ; sutures fairly 

 distinct, not channelled. The last whorl of the spire is lower 



"Bull. Amer. Pal., vol. 5, No. 29, p. 136, pi. 23, figs. 15, 16, 

 1917- 



