Logan.] The Invertebrates, Benton Group. 459 



behind the middle, rather depressed and incurved, with very 



slight obliquity ; posterior umbonal slope very obscurely angular 



from the beaks to the posterior basal extremity ; surface marked 



by lines of growth. Hinge line short, pallial line obscure. 



Length of large specimen, twenty mm. ; height, fifteen mm. ; 



convexity, eight mm. 



A cast of a shell which was taken from a thin stratum of 



sandstone underlying the Lincoln marble in the southern part 



of Mitchell county undoubtedly belongs to this genus, and 



probably to this species, although it resembles M. huerfanensis 



in a few points. Fragment of other forms resembling this one 



were found in the same horizon on the Solomon river near 



Beloit. On some of the casts the internal features are but 



poorly portrayed. 



Parapholas, sp. 



A piece of fossil wood collected by Mr. Sommers, of Buel, 

 from the Lincoln marble horizon of Salt creek, contains casts 

 of forms which resemble Parapholas sphenoides, with the ex- 

 ception that they are shorter and more robust. This species 

 may be synonymous with Parapholas f sp. Stanton, described 

 from the Pugnellus sandstone of Poison canon, Colorado. 

 Should such be the case, the circumstance points more clearly to 

 the identity of these two horizons. 



Turritella whitei Stanton. Plate xcix, figs. 1-5. 



Turritella urasana White, U. S. Geol. Surv. West 100th Mer., vol. iv, p. 



195, pi. xviii, ff. 11a and b. Not Turritella urasana Conrad, 1856, Pac. 



R. R. Rep., vol. v, p. 321. 

 Turritella whitei, Stanton, 1892, Bull. U. S. Geol. Surv. No. 196, p. 130, 



pi. xxvin, ff. 12-16. 



Original description: "Shell of ordinary size, elongate, 

 slender ; sides straight ; volutions numerous, apparently reach- 

 ing eighteen or twenty when full grown ; the sides of the volu- 

 tions nearly straight or only slightly convex; suture broad, 

 deeply impressed. Surface marked by numerous revolving 

 raised lines, six or eight of w T hich are moderately large, the 

 smaller ones alternating with them. The larger lines are mi- 

 nutely nodose upon the large volutions, and upon the last one 



