490 University of Kansas Geological Survey. 



A considerable fragment of a younger specimen is free from 

 them. Believing that ' he is a thoroughly good naturalist who 

 knows his own parish,' and in recognition of the valuable aid 

 rendered me in my studies of the geology of Kansas by his care- 

 ful work in the stratigraphy of his district, I have named this 

 shell in honor of its collector, Benjamin Brown, Esq., late of 

 Knebworth, England, who discovered it in the Fort Hays lime- 

 stone, at some ten to twenty feet above the base of the latter, 

 at a locality known as Devil's Gap, near the post-office of Top- 

 ley, in Osborne county, Kansas. 



" The woodcut of Inoceramus culverii given in Mantell's " Med- 

 als of Creation" (p. 408) strongly recalls the present shell, but 

 descriptions of the former seem to forbid reference of the latter 

 to it." 



It is a fact much to be regretted that no illustrations of this 

 specimen accompanied the above description. Especially as, to 

 my knowledge, none other of the Kansas collections contain 

 specimens of this species ; consequently it is not within the 

 power of the writer to figure it. On account of its large size, 

 fibrous structure, and the fact that it occurs in comparatively 

 durable limestone, there is little probability of many good speci- 

 mens of this species being obtained by collectors. 



Inoceramus concentricus, n. sp. Plate cxvi, fig. 1. 



Description : Shell semicircular, medium sized, almost flat, 

 slightly convex in anterior region ; hinge not prominent, curved, 

 umbonal region showing moderate depression ; beaks rounded 

 obtusely ; interior of valve smooth, not marked ; exterior surface 

 ornamented with concentric, prominent ridges, terminating near 

 beaks; ridges of surface rounded, smooth, marginal border of 

 last one marked by parallel lines of growth. Shell body mod- 

 erately thick, increasing slightly in thickness from central region 

 toward border. 



Length of longitudinal axis, 160 mm. ; height, 80 mm. ; 

 thickness, 4 mm. at margin, much thinner at greatest con- 

 vexity. Shell found with Ostrea conge sta attached to it by their 

 lower valves. 



