243 



Dorsal valve somewhat imiformly convex, but most prominently so 

 near the umbo; beak small, slightly prominent, mesial fold entirely want- 

 ing as a rule. Surface marked by faint traces of radiating striae and by 

 occasional imbricating lines of growth. 



Range and Distribution.— Upper Red Wall group and LoAver Aul)rey; 

 Carrixo Creek, at the confluence of White and Black rivers, and on either 

 side of White River in Maricopa County, and at Fort Apache and at 

 Jemez, NeAV Mexico, White River, Arizona, etc. Common throughout the 

 upper carboniferous of America and in England and India in the suii- 

 carboniferous also. Its range also extends into the Permian. 



MYALIXA de Konnick, 1844. 



MYALINA? 



Plate, Fig.13. 



The specimen here tigured in outline is too badly cruslied to warrant 

 a description, but is obviously a member of the genus Myalina. 



Position and Locality.— U]ip?i' strata of the Upper Red Wall, south 

 side of White River Canyon, one mile west of Fort Apache, Arizona. 



EUOMPHALUS Sowbery (1815). 



EUOMPHAUUS PERNODOSUS Meek and Worthen. 

 Plate, Figs. 14 a, b, c,e 

 White's description* (in part): "Shell rather above medium size when 

 full grown, nearly discoidal, the spire being only very slightly elevated, 

 and the inner portion of it l)eing quite flat, or evenly depressed. Test 

 thick, volutions five or six, the upper side flattened and sloping gently 

 inward to the distinct suture, outer side flattened, convex, under side 

 rounding; the angles formed by the upper and outer sides constitute a 

 distinct carina which is riigose or corrugated upon the outer volution; 

 upon the under side of the volutions there is a row of moderately large, 

 roimded nodes, separated by spaces of about their own width, those of 

 the last half of the outer volution being obsolete;" umbilicus not seen. 



■'U. S. Geog. Surv. W. of the lOOth lasridian, Vol. IV, P. 158, PI. 12, Figs. 2 a, b, c. 



