150 University Geological Survey of Kansas. 



and five or six on the shorter ; surface marked with moderately 

 distinct regular concentric striae. Length, 0.16 inch ; height, 

 0.10 inch." 



Range and distribution : Upper Coal Measures ; Grand Sum- 

 mit. 



A single worn specimen, probably of this species, is in the 

 University collection, from Grand Summit. The markings are 

 abraded, and most if not all of the shell is gone. However, 

 it agrees very well with the figures of the species given by Meek 

 in the base of the plate in the Nebraska report. 



Nucula ventricosa. Plate XXII, figs. 9, 9b. 



Nueula ventricosa Hall, Geol. Iowa, i, pt. n, p. 716, pi. xxix, ff. 5a, b, 

 (1858); Meek, Fin. Rep. U. S. Geol. Surv. Neb., p. 204, pi. x, ff. ITa-c, 



(1872). 



Meek's desription : "Shell small, thick, subovate, very con- 

 vex ; the greatest convexity slightly in advance of the middle 

 of the valve ; posterior ( shorter) end obliquely truncated from 

 the beaks to its narrowly rounded or subangular connection with 

 the base, rather deeply excavated just behind the beaks ; ante- 

 rior (longer ) end rather narrowly rounded, its most prominent 

 part being near or slightly above the middle ; dorsal outline de- 

 clining gently, with moderate convexity from the beak to the 

 anterior extremity ; basal margin forming a nearly semiovate 

 curve, being a little more prominent before than behind the 

 middle ; beaks convex, rather prominent, and placed about half 

 way between the middle and the most projecting part of the 

 postero- ventral extremity. Surface with (at least near the base) 

 fine, regular, concentric strise. Length, 0.42 inch ; height, 

 0.22 inch." 



Description of the cast : The posterior adductors are strongly 

 developed, ovate in outline, situated at the lower part of the 

 posterior extremity of the shell, nearly beneath the beaks ; pal- 

 lial line very heavily impressed, forming a somewhat oval curve. 

 Anterior adductor scars also prominent, considerably larger 

 and more circular in outline than the posterior, situated on the 

 upper side of the extremity of the umbonal ridge. Immedi- 

 ately to the rear of this are a pair of small pyriform impressions. 



