46 CARBONIFEROUS AMMONOIDS OF AMERICA. 



Affinities. — This species is certainly a variety of Pronorites cyclolohus 

 Phillips," but is more involute at the corresponding diameter, and has a 

 narrower umbilicus and a gi'eater number of lateral lobes. Specimens 

 described by de Koninck' from Belgium, and by Roemer" from the Hartz 

 Mountains in Germany, agree peifectly with the type of Pronorites cyclolo- 

 hus; the English, Belgian, and German beds, in which the S[)ecies was 

 found, are all in about the same horizon as the Ijed in which it was found 

 in Arkansas, and are considerably older than the Upper Carboniferous lime- 

 stone in which it was found in the Ural Mountains. From this Karpinsky** 

 thinks the variety uralensls represents a mutation from the type of the 

 species. 



The form from the Pyrenees described by Barrois^ as Goniatifcs cyclo- 

 lohus Phillips has been shown by Karpinsky to l)e a new s[)ecies, P. harrolsi 

 Karpinsky. This form is more evolute than even the type of P. cyclolohus, 

 and its lobes and saddles are broader and also less numerous. 



Occurrence. — Pronorites cyclolohus Phillips, variety nrkansasensis Smith 

 was found with Gastrioceras hranneri Smith in Arkansas, on Pilot Moun- 

 tain, Carroll County, 3^ miles southwest of Valley Springs, in T. 17 N., 

 R. 19 W., sec. 18, northeast corner, near the junction of the Chester lime- 

 stone of the Lower Carboniferous with the Lower Coal Measures or 

 " ^Millstone grit," but probably in the Chester stage, judging from the 

 occurrence of Productus cestriensis Meek and Worthen in the same beds 

 with the goniatite. The beds are called A 10 in Prof. H. S. Williams's 

 section; below them lie 55 feet of micaceous sandstones and shales (A U of 

 the section), and below that coarse, reddish-brown fossiliferous limestone, 

 belonging to the Chester stage of the Lower Carboniferous. 



The type figured on PI. XII, figs. 12-15, is the property of the U. S. 

 Geological Survey (National Museum), locality number 1275. 



Pronorites cyclolohus has been found in England in the u})per part of 

 the Mountain limestone; in Belgium in the limestone of Vise; in Germany 

 in tlie Kohlenkalk of the Hartz; and the variety uralensls has been found 

 in Russia in the Upper Carboniferous limestone of the LTral Mountains in 

 C 2 of the section. 



" Geol. Yorkshire, Pt. II, j). 237, PI. XX, figs. 40-42. 



''Faune calc. carl)on. de la Belgique, Vol. I, p. 273, PI. L, figs. .5 and 6. 



'■PaUcontographica, Vol. IX, p. 167, PI. XXVII, lig. 1. 



''Amiuoneeii der. Artiiisk-Stufe, p. 10. 



«M^m. Soc. Geol. du Nord, Vol. II, No. 1, p. 295, PI. XIV, fig. 2. 



