FOSSILS OF THE WAVERLY GKOUP. 257 



mine, Wahsatcli Range, Utah. Named in lionor of Prof. J. E. Clayton, of 

 Salt Lake Cit}-, Utah, to whom Ave are indebted for the use of the speci- 

 mens. 



ATHYBIS PLANOSULCATAi 

 Plato IV, iigs. 10-11. 



Compare AtliyHs i)I(inosuIcata Phil., Geol. Yorkshire, vol. ii, p. 220, fig. 15. 



^ A small species of Athyris not readily identilied with any known 

 species, and yet so closely resembling several described forms, that it is 

 difficult to cite differences which would distinguish it from them, occurs 

 associated with the fossils described from the Cottonwood divide It is of 

 medium size, neiirly circular in outline, Avith ventricose valves and destitute 

 of mesial fold or sinus; beaks small, that of the ventral valve incurved and 

 but slightly truncated by the small foramen. The surface of the shell is 

 smooth except from concentric lines marking stages of groAvth, and entirely 

 destitute of any marked or distinguishing feature. The specimens are of 

 the size and general appearance of those usually referred to A. planosulcata 

 Phil., and from its lack of distinguishing features we hesitate to refer it with 

 certainty to any known species. 



Formation and lomlity.—ln limestone of the Lower Carboniferous 

 (Waverly?) age, Cottonwood divide, 800 feet east of Reed and Benson's 

 mine, Wahsatch Range, Utah. Collected by J. E. Clayton. 



Genus RIIYNCHONELLA, Fischer. 



RUVNCnONELLA I'USTULOSA White?. 

 Plate IV, (jgs. iL'-ll. 



Rhynchonella imstulosa White, Jour. Bost. Soc. Nut. Hist., vol. viii, p. 226. 



Shell small, transversely subtrigonal, with a broadly rounded front and 

 straightened cardinal slopes; sides of the shell sharply rounded; beak 

 jjointed and projecting; valves ventricose, the dorsal the most gibbous. 



Surface marked by from sixteen to twenty-two simple rounded plica- 

 tions, five of which are elevated in the middle, to form the proportionally 

 broad mesial elevation, and a corresponding number depressed on the 

 ventral forming the siinis. 

 17 i> i; 



