Smith.] ^bO [Oct. 2, 



MM. 



Height of last whorl from centre of umbilifus 19 



Heiffht of last whorl from top of the inner one 8 



Width of umbilicus 9 



These measurements show the adult shell to be verj' globose. 



Position and Locality. — Several specimens of this very interesting spe- 

 cies were found in the Upper Carboniferous of Scott county, Arkansas, 1 

 X., 28 W., section 4, southeast quarter of southeast quarter, in beds sup- 

 posed to belong to the Barren Coal Measures ; but from this and asso- 

 ciated fossils seem more likely to belong to the Upper Coal Measures. 

 This species is also found in the Cisco division of the Texas Upper Coal 

 Measures. 



Oastrioceras exeelsum Meek, PI. xvii, Fig. 1. Ooniatites globulosus var. 

 excelsus Meek, Bull. U. 8. Geol. and Geog. Survey Terr., No. 6, 

 second series, p. 445. Goniatites globulosus Meek and AVorthen 

 (pars), Geol. Sure. Illinois, Vol. ii, p. 390, Fig. 38. 



This species was originally described from the Upper Coal Measures 

 of eastern Kansas, from Osage, associated with Spirifer cameratus 

 Morton, and Athyris subtilita Hall, and other species characteristic of 

 that horizon. 



It resembles closely in everything but size Gastrioceras globulosum 

 Meek and Worthen of the Upper Coal Measvires of Illinois, and we 

 know too few specimens of the latter species to say that it did not grow 

 to the immense size of the Kansas species. 



In the Lower Coal Measures of Pope county, Arkansas, 10 N., 20 W., 

 section 8, southeast quarter of northwest quarter, was found a large sep- 

 tate fragment of a specimen that must have been five or six inches in 

 diameter, since the body chamber is at least one coil in length on all 

 nearly related species. The ventral (external) portion of the shell is 

 higher and not so rounded as in G. globulosum, but as has already been 

 noticed on that species the coil becomes with age rounder and more ele- 

 vated, and this may be only an advanced stage of growth not seen on 

 any of the smaller specimens. The lobes are almost exactly like those 

 of the small Gastrioceras globulosum of Meek and Worthen. 



Gastrioceras marianum Y erne\x\, PI. xvi. Figs. 1-5. Goniatites mariamis 

 Verneul, Geol. of Russia, ii, p. 369, PI. xxvii, Fig. 2. Goniatites 

 jossce Verneul (pars), Eichwald, Let?i. Boss., i, p. 1324. Goniatites 

 listeri Martin (pars), var. 7Mario?, Gurow, Abhandl. d naturf. Gesell. 

 Charcoio, 1873, p. 87. Gastrioceras ■marianum Verneul ; Karpinsky, 

 Ammoneen der Artinsk-Stiife, p. 49. 



This is easily distinguished from all other American species l)y its low, 

 broad whorl, wide and deep umbilicus, and the strong ribs on the umbil- 

 ical shoulders. These together with its sutures make it a most typical 



