18%.] ^^'^ [Smith. 



"agression," ])y wliicli is meant a clianiie in the (lireetion of the spiral 

 iic:;()mpauied by widening of tlie umbilicus, so tliat witli age it Hares 

 open. Even witli the wide umbilicus of the adult stage, this species is 

 easily distinguished from (r. iiKiriarmm by its narrower and more highly 

 ai'clied whorls. 



The sides of tiie whorl are ornamented with strong tubercles, which 

 on the young stages are like those of G. mariunum, but on the adult 

 form ribs reach halfway from the umbilical shoulders to the ventral por- 

 tion of the shell. 



Constrictions are seen on the cast, aljout three or four to a revolution. 

 The surface of the shell is not known. The sutures arc like those of 

 G. maridnum, but the siphonal or external lobes are somewhat l)roader, 

 and the lateral lobes are longer, narrower and more pointed. 



Tlie lateral saddle is broad, rounded and considerably shorter than 

 the lateral lobes. There is also a small auxiliary or "sttspensive " lobe 

 on the uml)ilical shoulders, like that of G. marianiim. The sutures 

 resemble still more closely those of GlypMocer'as diadema Goldfuss as 

 figured and described by DeKoninck in Description des Animaux Fos- 

 siles Terr. Garhoiiif. Behjiqne, p. 574, PI. 1, Fig. 1, e. But the Belgian 

 species is considerably more involute, has a lower whorl, and propor- 

 tionally narrower umbilicus. Also the umbilical ribs are much weaker 

 than on the Arkansas species. 



Verneul, in Geol. Eiissie d' Europe et des Mont. Oural, Vol. ii, p. 367, 

 has described a goniatite as G. diadema, bitt this form is less like the 

 Arkansas species than the Belgian form. In addition to this, there is 

 no likelihood that all the forms referred to G. diadema are really one 

 species It is cxuite possible that the Arkansas species may be identical 

 with one of the many varieties ascribed to G. diadema, but at present it 

 is impossible to prove this. 



Occurrence. — Several badly broken casts and moulds were found in 

 the Upper Coal Measures of Scott countj', Arkan.sas, 1 N., 28 W., sec- 

 lion 4, southeast qtiarter of southeast quarter, associated with Gastrio- 

 ccras tiKirianum Verneul, G. (jlohulosum Meek and Worthen, Pi'o- 

 noritcs sp., etc. 



Genus Pabalegocekas, Hyatt. Paralegoceras iotoense Meek and 

 Worthen, PI. xix. Figs. 1-B. Goniatites iowensis Meek and Worthen ; 

 Geol. Surv. of Illinois, Vol. ii, p. 392, PI. xxx, Fig. 3. Paralego- 

 ceras iowense M. and W , Hyatt, Proc. Boston Soc. Nat. Hist., Vol. 

 xxii, 1883, p. 327. Paralegoceras ioicense M. and W., Hyatt, 

 Geol. Survey of Texas, Fourth Ann. Report, 1893, p. 474, Figs. 52- 

 55. Goniatites missouriensis Miller and Faber, Journ. Cincin. Soc. 

 Wat. Hist., Vol. xiv, p. 164, PL vi, Fig. 1. 



The genus Paralegoceras is extremely rare, being known lieretofore 

 only from the Coal Measures of Iowa, the Upper Carboniferous and 

 Artinsk beds of Russia, and the Bend Formation of Texas, and in the 

 Upper Coal Measures near Kansas City, Missouri. 



