DOUBTFUL SPECIES. 141 



Arcestidae the length of the body chamber is at least a revolution, and this 

 would almost double the size of the complete form. 



None of the species described by Gemmellaro are comparable with this 

 one; they are all more depressed and have less comj)licated digitation of 

 the lobes and saddles. The septa bear a greater resemblance to Hyattoceras 

 Gemmellaro," but that genus has the umbilicus entirely closed and lacks 

 the constrictions or varices; also its saddles, while phylliform, are distinctly 

 bipartite and not tripartite as in Waaqenoceras liilM. 



Occurrence. — Waaf/enoceras hUli was collected by W. F. Cummins in the 

 Double Mountain formation, Upper Permian, at the falls on Salt Croton 

 Creek, Kent County, Tex., associated with Popanoceras, Mecllicotfia, and 

 other forms possibly identical with those described by Dr. C. A. White '' 

 from the Wichita division. The type specimen was loaned the writer by 

 the late Prof Alpheus Hyatt. 



The name is given in honor of Mr. R. T. Hill, of the U. S. Geological 

 Survey, in recognition of his contributions to the geology of Texas. 



SPECIES NOT GENERICALLY IDENTIFIED. 



GONIATITES? COLUBRELLUS Morton. 



1836. Ammo7iites cohihreUm, S. G. Morton, Am. Jour. Sci., 1st series, Vol. XXIX, 

 p. 151, pi. 28, figs. 19 and .51. 



Shell discoidal, evolute, numerous convex volutions, laterally com- 

 pressed. Three or four constrictions to a revolution. 



Occurrence. — Upper Coal Measures, Cambridge, Guernsey County, Ohio. 



GoNiATiTES? MINIMUS Shumard. 

 1860. Goniatites minlmm Shumard. Trans. St. Louis Acad. Sci., Vol. I, p. 200. 



Shell subglobose, involute, deeply embracing; breadth equal to three- 

 fourths of diameter. Abdomen and sides strongly rounded. Umbilicus 

 minute, not showing the inner whorls. Surface ornamented with exceed- 

 ingly iine spiral lines; and obscure nodes, visible on the umbilical shoulders. 

 Occurrence. — Middle Coal Measures, near Dovers Landing, Missouri. 



"Fauna calc. FiLsulina, p. VI. ^Bull. U. S. Geol. Survey No. 77. 



