122 University Geological Survey of Kansas. 



Range and distribution: Upper Coal Measures; Topeka. 

 From the horizon of the Osage coal. 



The fine, regular, cancellated striae and the larger striae on 

 the anterior ear distinguish this species from any of the pre- 

 ceding. We have a single specimen from Topeka which seems 

 to agree very well with this species. 



Aviculopecten sculptilis. Plate XIII, figs. 3, 3b. 



Aviculopecten sculptilis Miller, 17th Ann. Rep. St. Geol. Ind., p. 702, pi. 

 xx, f. 5, (1892). 



Shell a little large, somewhat oblique, ovate in outline, taper- 

 ing to the beak at an angle of 90° or less, very moderately con- 

 vex ; beak extending to or a trifle beyond the hinge line, and 

 located back of the middle of it. The ears are small, the 

 anterior flattened, and separated from the swell of the umbo by 

 a deep depression, and considerably larger than the posterior 

 ear ; the margin of the ear makes a deep sinus at its junction 

 with the margin of the shell ; however, the anterior border of 

 the shell generally extends beyond the ear ; posterior ear small, 

 well defined, margin not separated from the margin of the shell 

 by a very distinct sinus ; the posterior is about two-thirds as 

 long as the anterior. Both ears (in the left valve) are marked 

 by small, well defined, concentric striae. Entire border below 

 the ears regularly rounded and subsemicircular. The shell is 

 marked by numerous, closely set radiating striae, which are 

 crossed by about equally prominent closely set concentric striae, 

 giving the shell a beautifully cancellated appearance ; the radi- 

 ating striae increase by implanation. At the anterior border 

 the shell often becomes quite rough in appearance on account 

 of the enlarging of the striae. The anterior ear seems to be 

 crossed by a few indistinct radiating striae. According to Mil- 

 ler, the anterior ( " posterior " ) ear of the right valve is marked 

 by more prominent radiating striae which "give it a strongly 

 pitted aspect." Measurements: Height, 49 mm. ; length, 40 

 mm. ; length of hinge, 23 mm. ; convexity, about 8 mm. 



Range and distribution : Upper Coal Measures ; Kansas City. 

 Taken from the oolite. 



