FOSSILS OF THE LOWER CARBONIFEROUS. 271 



compression, but the features of the species are so well and distinctly 

 represented on it that it is impossible to doubt its identity. 



Formation and locality. — In limestone of Lower Carboniferous age, 

 north of Snowstorm Hi^d, Dry Canon, Oquirrh Mountains, Utah. Collected 

 by J. E. Clayton. 



Spikipeea — sp. ?. 



Plate 5, flg. 16'. 

 Compare Spirifera imhrex Hall, Geol. Iowa, vol. 1, pt. ii, p. 601, pi. 13, fig. 2. 



The figure is of a fi'agment of a cast of the ventral valve in chert, from 

 a fragment of the Weber quartzite, a rock usually destitute of all organic 

 remains, and it is for this reason only that the specimen has been figured. 

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

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

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

 bifurcations, still the direction and number 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. imhrex Hall from the Bur- 

 lington limestone of the l^ower Carboniferous formations, at Burlington, 

 Iowa (Iowa Geol. Eept, vol. 1, pt. ii, p. GOl, pi. 13, fig. 2), and it is even 

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

 is unknown to us, we are unable to determine positively. The plications 

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

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

 species where the bifurcations are but few. 



Formation and locality. — In the Weber quartzite, Bear Eiver, Uinta 

 Range, Utah. Collected by Clarence King, esq. 



Genus ATHYRIS McCoy. 

 Atuykis subquadrata ?. 



Plate 5, fig.s. 19-20. 

 Athyris snhquadrata Hall, Geol. Iowa, vol. 1, pt. ii, p. 703, pi. 27, fig. 2. 



Shell of medium size, varying from irregularly circular to distinctly 

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



