FOSSILS OF THE LOWER CARBONIFEROITH. 271 



compression, l)iit the icaturt's of tlie spiH'ics are .so wt'll unci distinctly 

 represented on it that it is inip(issil)lc to donht its identity. 



Formatioit and Jocalitii. — In limestone of Lower (Jarbonil'eroiis age, 

 north of Snowstorm lli'J, Dry Canon, ()(jnirrh Monntains, Utah. Collected 

 by J. E. Clayton. 



Spibifeea sp. ?. 



Plater,, iig. III. 



Compare Spirifera imbrex Hall, Gt'ol. Jowa, vol. 1, pi. ii, [>. (JOl, pi. 13, fig. 2. 



The figure is of a fragment of a east of the ventral valve in chert, from 

 a fragment of the Weljer cpiartzite, a rock usually destitute of all organic 

 I'emains, and it is for this reason only that the specimen has been figured. 

 It is of a species possessing numerous sharplv-elevated, angular plications, 

 simple on the sides of the shell, and apparently Infnrcating in the mesial 

 sinus; although the example does not furnish positive evidence of such 

 bifurcations, still the direction and munber would indicate such to be the 

 case. The plications have been crossed by closely-arranged, strong, zigzag, 

 concentric lines; which give a strongly roughened surface to the cast. The 

 only species having strong affinities with it is S. imbrex Hall from the Bur- 

 lington limestone of the Lower Carboniferous formations, at Burlington, 

 Iowa (Iowa Geol. Rept., vol. L pt. ii, p. (!'>1, pi. L''), fig. 2), and it is even 

 probable that it may be identical; but, as the ventral valve of that species 

 is unknown to tis, we are unalde to determine positi\-eh-. The plications 

 of that species often bifurcate on the upper part of the shell, while these 

 are simple; but this featnre may not hold good on all specimens of the same 

 species where the bifurcations are Init few. 



Formation and Jocalit//. — In the '\\'el)er (piartzite, Bear River, Uinta 

 Range, Utah. Collected b\- (Jlarence King, esq. 



Genus ATIIYRIS McCoy. 



ATH YRIS SlBy UADUATA ?. 



Pi.it.. r,. tigs, i;i--,o. 

 Athyris Huhquadrata Hall, Geol. Iowa, vol. 1, |)t. ii, p. 703, pi. 27, tig. 2. 



Shell of medium size, varying from irregularly circular to distinctly 

 quadrate in ontline, with more or less ventricose valves; length usually 



