126 University Geological Survey of Kansas. 



Pteria sulcata. Plate XVI, fig. 3. 



Gcrvillia sulcata Geinitz, Carb. u. Dyas in Neb., p. 33, pi. n, f. 16, (1866). 

 Aviculaf sulcata Meek, Fin. Rep. U. S. Geol. Surv. Neb., p. 200, pi. ix, f. 



9, (1872). 



All the specimens before me having the ears either broken off 

 or not visible, Meek's description of Geinitz's figure is given, 

 with remarks on the specimens at hand. " Rhombic oblique 

 shell, with short, compressed, triangular anterior ear, defined 

 by a faint, wide marginal sinus ; and a larger compressed, some- 

 what elate, posterior ear, with a marginal ridge, showing a 

 tendency to be produced into a narrow appendage behind, sepa- 

 rated from the margin below by a rather deep, rounded sinus. 

 The posterior basal extremity is rather narrowly rounded, but 

 not much produced ; while the outline of the base is broadly 

 semielliptical, and the umbo convex, and rising somewhat above 

 the hinge line, which is apparently shorter than the greatest 

 length of the valve. Surface ornamented by fine lines of growth , 

 and before by two or three sulci, extending from the anterior 

 side of the beak to the antero-basal margin, leaving ridges be- 

 tween which are more or less crenated by the crossing of the 

 marks of growth; just behind the posterior one of these sulci, 

 the margin of the latter is ornamented with regular, rather 

 strongly defined wrinkles, or little folds, some of which are pro- 

 longed backward parallel to the lines of growth." 



Range and distribution : Upper Coal Measures ; Kansas City, 

 Lawrence. 



Most of our specimens are younger than the one figured by 

 Meek and Geinitz, and, as a result, somewhat less ornamented. 

 The ornamentation is varied somewhat in different individuals. 

 In some the ridge between the sulci is very crenate, and less so 

 in the others. It may easily be distinguished from the other 

 species by the ornamentation of this part of the shell. 



