448 University of Kansas Geological Survey. 



the average size, from umbo to basal margin, about one cm. ; 

 breadth, eight cm. ; convexity of larger valve, nearly six cm." 

 A form found imbedded in a firm matrix of Lincoln marble I 

 think belongs to this species ; if so, it is a young individual. 

 Specimen was found associated with Exogyra Iseviuscula in the 

 Lincoln marble outcrops, on Rattlesnake creek, Lincoln county. 



Exogyra Iceviuscula Roemer. 



Exogyra Iceviuscula Roemer, 1852, Kreid. von Texas, p. 70, pi. ix, ff. 3a-c; 

 Conrad, 1857, U. S. and Mex. Bound. Surv., p. 154, pi. vir, ff. 4a, b; White, 

 1876, U. S. Geog. and Geol. Surv. West 100th Mer., p. 173, pi. xvn, ff. 2a-d; 

 1884, 4th Ann. Rep. U. S. Geol. Surv., p. 305, pi. lii, ff. 3, 4, 5; Stanton, 

 1892, Bull. U. S. Geol. Surv. No. 196, p. 64, pi. vm, ff. 5 and 6. • 



O street ferdinandi Coquard, 1869, Mon. Gen. Ostrea, Terr. Cret., p. 33. 



Exogyra ponderosei Hill, 1889, Check List Cret. Invert. Fossils of Texas, p. 6. 



Description : Shell moderately capacious and semiovate in 

 form ; test moderately thick ; general shape of shell varying in 

 outline from subovate to suborbicular ; inferior valve inflated 

 and very much curved and rounded in outline. Superior valve 

 smaller and nearly flat, suborbicular in outline ; surface smooth 

 but marked by very faint lines of growth. Umbo small, coiled 

 pirally, forming two volutions which are narrow and closely 

 involuted ; hinge line short ; scar of attachment small or want- 

 ing ; umbo in some specimens somewhat free. Diameter from 

 umbo to basal margin, forty-seven mm. ; transverse diameter, 

 forty-two mm. ; depth of the larger valve, eighteen mm. 



Species occurs in the Lincoln marble, but is not abundant. 

 The only specimens found were collected from the outcrops on 

 Rattlesnake creek, in the northern part of Lincoln county. 



Avicula gastrodes Meek. Plate lxxxvi, figs. 8, 9. 



Avicula {Oxytoma.') gastrodes Meek, 1873, Ann. Rep. U. S. Geol. Surv. fo 



1872, p. 491. 

 Pteria (Oxytoma) qastrodes White, 1879, Ann. Rep. U„. S. Geol. Surv. Terr. 



for 1877, p. 280, pi. x, f. la. * 



Pteria (Oxytoma ) c recta White, 1880, Proc. U. S. Nat. Mus., vol. in, p. 157, 



and vol. iv, ff. 7 and 8 of plate opposite p. 139. 

 Avicula gastrodes Stanton, 1893, Bull. U. S. Geol. Surv., p. 72, pi. ix, ff. 7-10. 



Description: "Shell (as determined from a left valve) at- 

 taining a moderately large size, subtrigonal in general outline, 

 rather distinctly convex, and having a very slight backward 



