FOSSILS OF THE DEVONIAN. 



187 



Genus ECOULIOMPHALUS Portlock. 



Ecculiomphalus Devonicus, n. sp. 



Plate vi, figs. 6, 6 a. 



Shell discoid. Volutions, one or two?, widely separated; rapidly 

 enlarging; section subtriangular, rounded a little above and also from the 

 inner and outer margins down to the obtusely angulated ventral surface. 



Surface unknown. 



A comparison with the figures given by Portlock of the types of the 

 genus E. Bucklandi and E. minor (Rep. Geol. Londonderry, Tyrone, &c., 

 1847, pp. 411, 412, pi. xxx, figs. 10-12) shows our Devonian species to be 

 generically identical with them, although the inner portion of the whorl or 

 whorls is broken away, and the surface of the shell destroyed. 



Formation and locality. Lower Devonian of Atrypa Peak; Eureka 

 District, Nevada. 



Genus STRAP AKOLLUS Montfort. 



Straparollus Newarkensis, n. sp. 



Plate xvi, figs. 7, 7 a. 



Shell small ; spire slightly elevated above the general plane Umbili- 

 cus narrow, scarcely exposing the inner whorls. Volutions four or five, 

 very gradually expanding to the outer volution, which increases a little more 

 rapidly; transverse section rounded, subangular or obscurely subquad- 

 rangular; obtusely angular above and below with a slightly .oblique, convex, 

 or flattened periphery; gently rounded on the upper surface to the strongly 

 defined suture, and on the lower surface to the more sharply rounded edge 

 of the umbilicus. 



Surface of the shell marked by concentric striae and lines of growth 

 parallel to the margin of the aperture. From the suture they curve slightly 

 backward over the upper margin, and then forward to a little below the 

 center of the periphery, recurving gently backward to the margin of the 

 umbilicus. 



