82 PALEONTOLOGY OF THE EUREKA DISTRICT. 



Formation and localities. Strata of the Pogonip Group, north slope of 

 White Mountain, 500 feet below the summit; east slope of ridge east of the 

 Hamburg mine, Eureka District, Nevada, The species also occurs at the 

 same horizon on Pogonip Ridge, White Pine District, Nevada. 



Maclurea subannulata, n. sp. 

 Plate xi, figs. 18, 18 a- 6. 



Shell about twice the size of the preceding species and presenting all its 

 essential features of a flat lower surface and deeply umbilicate or depressed 

 upper side. It differs in the more rapidly increasing size of the volutions, 

 their more elongate semioval section, more rounded periphery, and in the 

 cast being obscurely annulated but in a reverse manner from what would 

 be the case if the annulations of the outer shell of M. annulata were present 

 on the cast; the constrictions, instead of being narrow, are quite broad and 

 the annulations narrow. 



Formation and locality. Pogonip Group, north slope of White Mountain, 

 Eureka District, Nevada. 



.> 



Maclurea carinata, n. sp. 

 Plate xi, figs. 20, 20 a. 



Shell small, general form thick, discoidal; greatest diameter, 20 mm ; 

 height of outer whorl, 6 mm ; spire depressed to form a broad, shallow, um- 

 bilical-like area; lower side nearly flat, or with a slight umbilical depression 

 of the inner whorl; volutions about three, increasing very regularly in size 

 with the growth of the shell; slightly convex on the lower side, terminating 

 in a decided carina on the periphery, where it unites with the slope of the 

 side; the sides of the whorl are steep, and equal in depth to the width, the 

 carina at the lower outer margin of the inner whorls resting in the sutures 

 of the umbilical side. 



Surface of the lower sides of the whorls marked by numerous strong 

 striae that arch across the whorl and forward over the carina; their course 

 on the upper side has not been observed. 



