Smith.] 262 [Oct. 2, 



the shell. Angle of umbilicus with the axis of the shell about 87^^. 

 These measurements agree very Avell with those given by Karpinsky. 



The smallest of the Arkansas specimens gave the following dimen- 

 sions : 



MM. 



Diameter 8.5 



Height of last whorl "2.5 



Width of umbilicus 4.5 



Breadth of last Avhorl li.O 



These measurements agree closely with the measurements Karpinsky 

 gives of small specimens from the Urals. The proportions would be 



Diameter 1.00 



Height of last whorl .... 0.29 



Width of umbilicus 0.53 



Breadth of last whorl 0.70 



These proportions agree very well with those given by de Verneul, 

 Geol. Russie cV Europe et des Mont, de V Oural, Vol. ii, p. 369. 



Occurrence. — This species was originally described by Verneul from 

 the Upper Carboniferous limestone of Schartymka in eastern Russia, 

 C2, and does not occur in the Artinsk or Lower Permian deposits, 

 although it has been confused by many authors with Gustrioceras 

 jossce, which is characteristic of those strata. Karpinsky, in his mono- 

 graph on the Ammoneen der Artinsk- Sti/fe, pp. 50 and 51, describes the 

 differences that separate G. marianum from G. jossce and G. listeri; 

 the most striking of these distinctions is that on G. mariamim the con- 

 strictions have a weak sinus pointing backward, while on the others it 

 is forward. 



We have therefore at least some evidence of an Upper Carboniferous 

 sea, stretching from the Ural mountains eastward to the Mississippi 

 valley. This would help to explain the fact that our marine Carbonifer- 

 ous fa\ma has more analogy to the Asiatic than to the western European 

 fauna of the same age. 



G. marianum was found in the Upper Coal Measures in Scott county, 

 Ark., 1 N., 28 W., section 4, southeast quarter of southeast quarter. 

 This, or a very closely related species, occurs also in the Cisco division 

 of the Upper Coal Measures of Texas. 



Gastrioceras, sp. indet. PI. xx. Fig. 1. 



In the young stages this species resembles closeh' G. marianum Ver- 

 neul, bnt the umbilicus is nariower. The young whorl has also a 

 trapezoidal cross-section, each succeeding whorl becoming more highly 

 arched, until all resemblance to the Ural species is lost in the adult 

 stage. 



The coil, too, sliows decidedly the plienouKMion calK'd by ^lojsisovics 



