SHl'MARDITES. 135 



antisiplional lobe, bifid first lateral lobe, and undivided second lateral lobe. 

 Internal saddles rounded like the external. 



In youth the form of the whorls is gastrioceran, like Gastrioceras 

 ghhulosum Meek and Worthen, and G. snbcavum Miller and Gurley; the 

 constrictions, form of the whorls, and the obscure traces of umbilical nodes 

 all point to a gastrioceran ancestor, but the septa show a transition to the 

 primitive Arcestidae. A small specimen showed gastrioceran characters at 

 diameter of 7 mm., and those of Schistoceras at diameter of about 10 mm., 

 but the transition to Shumarditcs takes place very quickly toward maturit}-. 



In form this genus is a goniatite, but the septa have already made the 

 transition to the annnonite stage of development; it might be placed with 

 the Glyphioceratidaj, because of the gradation' through Gastrioceras, 

 Paralegoceras, and Schistoceras; l^ut it is the most primitive of the Arcestes- 

 like forms, and might with equal propriety be classed with the Arcestidae. 

 The nearest known genus is Hyattoceras Gemmellaro, of the Sicilian 

 Permian, but Shumardites lias simpler septa than that geniis, and may very 

 possibly be the ancestor of it. The arrangement and shape of the lobes in 

 Waacjenoceras and other similar genera show that they have developed out 

 of some genus like Shumardites. Now, since Cyclolobus, Waagenoceras, and 

 Hyattoceras all show a common ancestry in Shumardites or in some similar 

 form, it is proper to group them all under the family Cyclolobidse of Zittel, 

 but excluding from this family the genera Lohites, Stacheoceras, Fopanoceras, 

 Frocladiscites, Meyapliyllites, and Monophyllites. Since Adriunites, Popan- 

 oceras, and Stacheoceras all seem to have been derived from Agathiceras, it 

 is proper to class them under the family Popanoceratidae of Hyatt. 13oth 

 families together would make up the Paleozoic superfamily Arcestida;. 

 But a single species of Shumardites is known, .S'. simondsi sp. nov., of the 

 Upper Coal Measures, Cisco formation, or Missourian stage, of Graham, 

 Young County, Tex. The generic name is given in honor of Dr. B. F. 

 Shumard, the first State geologist of Texas. 



Shumaridites simondsi Smith, sp. nov. 

 PI. Ill, figs. 8-13. 



Shell subglobose, breadth equal to more than two-tliirds of the diame- 

 ter; evolute; whorls highly arched, helmet-shaped, twice as wide ;is high, 



