CARBONIFEROUS CEPHALOPODS. 351 



or dorsal zone is only 35 mm. in diameter, showing that the next internal 

 whorl must have been very small compared to the outer one. The sutures 

 have the typical form, with narrow, angular ventral saddles. The septa are 

 divided by a median ridge internally, as in other forms of this genus. 



The principal differences between this species and its nearest congener, 

 Ephip. bilobatum of Europe, lies in the extraordinarily rapid increase of the 

 lateral diameters of the whorls by growth and the enormous breadth of the 

 last whorl. The lateral lobes are not so long, and the saddles at the umbili- 

 cal shoulders not so deep in the specimen described, but this may be more a 

 matter of age. Fragments of the shell still remain on the cast of the living 

 chamber, and these are smooth. 



The Nautilus clitellarius, as figured by De Verneuil* is a small shell with 

 open umbilici not at all similar to the fossil described above or to the true 

 Epiph. bilobatum or clitellarium and we propose to call this Ephippioceras Ver- 

 nuili. The Naut. clitellarius, Trautschold, also from Russia, j- is a fragment, 

 and may be the same, since although a fragment and considerably larger the 

 sutures are similar to those of the last named. Nautilus divisus, as described 

 and figured by White and St. John, is a closer ally than the Russian species, 

 but their figure differs in not having the depressed zone along the abdomen, 

 and the abdomen is apparently not so broad and depressed. The sutures are 

 similar, having similar shallow lobes and not very prominent ventral saddles. 

 The drawing is, however, in perspective, and the appearance of the sutures 

 may be deceptive. While awaiting more evidence it has been thought best 

 to adopt the name given by White and St. John for the Kansas and Texas 

 fossils. 



Epiph. (Nautilus) clitellarius, as first figured by J. de C. Sowerby,| is very 

 like the adult of the Kansas fossil, if the drawing is accurate. This shell 

 had, however, probably reached its maximum, or was nearly full grown; 

 and if it were projected to the size often attained by the Kansas form 

 would perhaps have a much broader and larger whorl. Accurate com- 

 parisons of good examples of these shells are needed before it can be posi- 

 tively decided that clitellarius, J. de 0. Sowerby, bilohatus, Sow., and this form 

 are not identical. The cast of a little shell figured by Fischer de Waldheim,|| 

 under the name of Goniatites ovoideus is similar to biblohatum, Sow , as figured 

 by De Koninck, but the figure, unless it is inaccurate, is not like what the 

 young of E. divisum must have been. Cyrtoceras Fahrenkohli, figured by the 

 same author on the same plate, may be identical with this, as claimed by De 



* Russia and the Ural Mts. Pal., PI. 25. 



f Nouv. Mem. de la Soc. Imp. de Nat. de Moscow, XIII, 1874, PI. 30, Fig. 4. 



X Bull. Soc. Nat. de Moscow, 1848, Part III, p. 132, PI. 5, Fig. 3. 



|| Prestwich, G-eol. Coalbrookdale, Trans. G-eol. Soc. London, 2d ser., V, p. 492, PI. 34, Fig. 5. 



