84 CARBONIFEROUS AMMONOIDS OF AMERICA. 



are three in number, a long, narrow, pointed antisiphonal lobe, and a pair 

 of shorter, pointed lateral lobes; the four internal saddles are rounded. 

 The figures on PI. XI, figs. 12 and 13, show the sutures to be characteristic 

 of Gastriocerns ; but the second lateral lobe, while on the umbilical 

 shoulders, is plainly visible from the outside. Thus the species might be 

 referred to the genus Paralegoceras of Hyatt; but it has only nine lobes 

 and nine saddles, while Paralegoceras has eleven of each. 



Surface characters. — The shell is preserved on only a small portion of 

 the specimen, but the cast shows the generic and specific characters qiiite 

 as well. Obscure and somewhat doubtful constrictions were obsei-ved, but 

 the preservation is such that their interval could not be ascertained. The 

 umbilical shoulders are marked with rather weak nodes or ribs, which on 

 the outer whorls reach up nearly to the abdominal shoulders ; on the young 

 shell they are relatively much stronger. 



Affinities. — Gastrioceras hranneri belongs to the group of G. listeri 

 Martin, G. josscpYerneuil, and G. marianmn, all characterized by trapezoidal 

 cross section, umbilical ribs, pointed lobes and rounded saddles, and evolute 

 whorls. From the above-mentioned species G. hranneri differs in the nar- 

 rowness of its whorls, and wide, shallow umbilicus; it seems to depart 

 further from the Glyphioceras stock than any other Carboniferous species of 

 the genus Gastrioceras. 



Occurrence. — Gastrioceras hranneri was found along with Pronorites 

 cyclolohus Phillips, var. arhansasensis Smitli, and Productus cestriensis Meek 

 and Worthen, in Arkansas, on Pilot Mountain, Carroll County, 3J miles 

 southwest of Valley Springs, in T. 17 N., R. 19 W., sec. 18, northeast 

 corner, in Lower Carboniferous, Chester group (AlO of Prof H. 8. 

 Williams's section). 



The tjq^e, for the use of which the writer is indebteil to Prof H. S. 

 Williams, is the property of the U. S. Geological Survey (U. S. National 

 Museum), locality number 1275. 



Gastrioceras carbonarium von Buch. 



Plate XI, figs. 1-4. 



1832. AmmonHes carlxmariue: (pars), L. von Buch, Phys. Abhandl. BerHii Akad. der 

 Wissenschaften for 183U, p. 170, PI. II, tig. 9 iv, (not !», H i-ni). 



1842. Goniatites carhmiariiu^ (pars), d'Archiac and Verneuil, Trans. Geol. Soc. 

 London, 2d series, Vol. VI, p. 382. 



