102 University Geological Survey of Kansas. 



area subtriangular, being moderately high under the beak, but 

 narrowing rapidly, with moderately defined concave margins, 

 to the extremities of the hinge, and arching with the beak ; 

 fissure rather narrow, or higher than wide, apparently rounded 

 above under the beak, and spreading at the hinge." Measure- 

 ments : Length, 9 mm. ; width, 10 mm. ; convexity, 5 mm. 



Range and distribution : Upper and Lower Coal Measures ; 

 Fort Scott, Fredonia, Eudora, Lawrence, Lecompton, Topeka, 

 Emporia. 



RETICULARIS. 



McCoy, Carb. Foss. Ireland, p. 142, (1844). 

 Waagen, Pal. Indica, ser. xiii, I, p. 538, ( 1893). 



Reticularia perplexa. Plate XII, figs. 4-4c. 



Spirifer lineatus Shumard, Geol. Surv. Mo., p. 216, (1855); etc. 



Spirifer perplexus McChesney, New Pal. Foss., p. 43, (1860). 



Spirifer lineatus var. perplexus Swallow, Trans. St. L. Acad. Sci., n, p. 



408, (1866). 

 Spirifera lineata Meek, Fin. Rep. U. S. Geol. Surv. Neb., pi. n, f. 3 t 



(1872); etc. 

 Spirifer { Marti nia) perplexa Derby, Bull. Cornell Univ., p. 16, pi. in, 



ff. 27, 39, 40, 45, 50, pi. vm, f. 13, (1874). 

 Spirifer (Martinia) lineata f White, Wheeler's Expl. Surv. West 100 1 " 



Mer., in, Appendix, (1881); later without query; etc. 

 Spirifera perplexa Keyes, Geol. Surv. Mo., v, p, 84, (1895). 

 Reticularia perplexa Schuchert, Bull. U. S. Geol. Surv. 87, p. 342, (1897). 



White's description: "Shell moderately gibbous, trans- 

 versely subelliptical in marginal outline, the front and sides 

 regularly rounded ; hinge much shorter than the width of the 

 shell ; cardinal extremities rounded ; cardinal area distinct, 

 arched, and moderately high ; ventral valve convex ; umbonal 

 portion prominent; beak prominent, incurved; area small,, 

 without median sinus, but there is a slight flattening of the 

 valve in front, which gives the front margin a slight sinuosity; 

 dorsal valve regularly convex, both transversely and longitudi- 

 nally ; umbonal portion prominent, but not so much so as that 

 of the other valve ; beak moderately prominent and projecting 

 a little beyond the hinge line ; surface marked by very numer- 

 ous very faint radiating lines and somewhat stronger concentric 

 lines, the latter being impressed and finely crenulate, the 

 minute crenulations apparently marking the bases of hair-like- 



