158 University Geological Survey of Kansas. 



parallel to the ventral margin. Surface smooth, showing oc- 

 casional very faint undulations of growth. Length, 31 mm. ; 

 height at beak, 21 mm. ; convexity of single valve, 5 mm. 



Range and distribution : Upper Coal Measures ; Lawrence. 



There is but little doubt that our shells are specifically iden- 

 tical with Herrick's specimen, as far as can be learned from his 

 figure and brief description. At any rate, our spec*ies is not S. 

 wheeleri! It is much more nearly related to S. chesterensis M. 

 and W., from the Chester group of Illinois. The beak is less 

 elevated and placed farther back, the shell is less convex, and 

 the posterior adductor scar is placed farther forward than in 

 that species. It bears some resemblance to S. meekanus Girty, 1 ' 2 

 but the beak is a little less prominent, the shell less elongate, 

 and the ventral margin curves up more rapidly posteriorly, the 

 posterior angle being nearer the hinge line than in that species. 



A large number of these shells have been collected from the 

 dam rock at Lawrence, and from its equivalent at Cameron's 

 Bluff. They all agree well with the above description and rep- 

 resent a distinct species. 



SOLENOMYA. 



Lamarck, Hist. Nat. Anim. sans Vert., V, p. 488, (1818). 



Solenomya parallella. Plate XXI, fig. 1. 



Solenomya parallella Beede and Rogers, Kans. Univ. Quart., v'ni, p. 131, 

 pi. xxxiv, f. 1, (1899). 



Shell large, moderately convex, elongate-subquadrate in out- 

 line ; anterior margin broadly rounded to nearly truncate, 

 meeting the hinge at a little more than a right angle ; dorsal 

 and ventral margins straight, nearly parallel; postero-dorsal 

 margin sloping obliquely downward, meeting the rounded pos- 

 terior margin at an obtuse angle. Beaks depressed, incurved, 

 situated about one-fourth the distance from the posterior to the 

 anterior end of the shell. The greatest convexity is at the 

 umbo, the shell gaping a little wider anteriorly than behind. 

 Surface marked by flat, radiating plications, which become 



obsolete at either end of the shell, the whole surface of which 



. i_ 



12. TJ. S. Geol. Surv., 19th Ann. Rep., pt. Ill, p. 583, pi. LXXII, ff. 7a-c, ( 



