LOWER CARBONIFEROUS FOSSILS. 577 



same block of limestone which carries the pygidium referred to P. loganensis. 

 They are without surface ornamentation. The occipital ring is narrow and 

 not strongly marked. The glabella is moderately high, reaches nearly to 

 the anterior margin, evenly rounded in front, about once and a half as 

 long as wide, sides parallel the greater distance, but expanding suddenly 

 behind. Marked by three or four pairs of transverse furrows. Of these, 

 only the posterior one. is well defined, and it is bent backward at its inner 

 end so as to be almost continuous with the occipital furrow. Frontal border 

 narrow, thick, elevated. Greatest width of the anterior portion of the 

 head, as limited by the suture line, just equal to the length of the glabella. 

 The suture lines contract gradually, but round out strongly for the palpe- 

 bral lobe, the most convex portion of which is not more than one-fourth the 

 length of the head, forward from the posterior edge. 



Formation and locality: Madison limestone, east side of Gallatin 

 River, west of Electric Peak; G. M. Wright. Crowfoot Ridge, Gallatin 

 Range, bed 31; J P. Iddings and W. H. Weed. East slope of Survey 

 Peak, Teton Range; S. L. Penfield. Waverly age, Ogden and Logan 

 canyons, Wasatch Range, and Dry Canyon, Oquirrh Mountains, Utah. 



Proetus loganensis Hall and Whitfield. 



PI. LXXI, fig. 15a. 



Proetus loganensis Hall and Whitfield, 1877: King's TJ. S. Geol. Expl. 40th Par., Vol. 

 IV, p. 264, PI. IV, fig. 33. 



The identification of this species rests upon a single pygidium which, 

 but for being considerably smaller in size, is exactly identical with that 

 figured as the type of P. loganensis. The surface is without ornamentation. 

 The axial lobe is high, marked by eleven annulations including the termi- 

 nal ones. The lateral lobes have nine annulations each, which extend 

 down upon the border and become obsolete upon the margin near the edge 

 of the shell. It occurs associated with P. peroccidens. 



Proetus peroccidens and P. loganensis, both of Hall and Whitfield, rest 

 upon three structural units — a small unornamented pygidium, a large 

 pygidium with more annulations, ornamented with pustules or nodes, and a 

 head with free cheeks more nearly corresponding in size witli the larger 

 pygidia, but destitute of the ornamentation which characterizes them. The 



3ION XXXII, TT II 37 



