76 CARBONIFEROUS AMMONOIDS OF AMERICA. 



iKiutiloid; metanepionic, Anarcestes of Lower Devonian; paranepionic, Parodoccras 

 of iliddle Devonian; neanic, Prlonoceras of Upper Devonian and Carboniferou.s, 

 showing gradual transition through ana-, meta-, and parancanic, and a gradual 

 change from Prkmoceras to Gonlatites in the late adolescent and early adult stages. 

 Piionoceras or some similar form seems to have been thc.faniil}^ radicle, and A<jan- 

 ides is a side branch, since Goniatites does not go through any stage corresponding 

 to the latter genus. Gmtr/'orrras comes from l^rionocefas (through (jh/jdiidccrdt) by 

 somewhat narrowing the whorl and division of the ventral lol>e. GlypJtiuCfms and 

 Goniatites come directly from Prlonocenm by narrowing the umbilicus so as to 

 conceal most of the inner whorls, and by division of the ventral lobe. 



The division of the family Glyphioceratidie iwto Ag an Idea, I'rlonoceras, Goniolo- 

 boceras, Dlmorphoceras, Pe)'icychis, Goniatites, Glypliioceras^Munsteroceras, Gastrio- 

 ceras, I'arah'goceras, and Sc/u'-stoceras is quite proper for phylogenetic reasons. 



According to Steinmann the Ceratitida; of the Trias are descended fi-om Gastrio- 

 eeras, and the Tropitidffi from Pericydus, but neither of these groups goes through 

 stages of growth corresponding to these genera. Tniptfts does, however, go through 

 a Prlonoceras stage, and later it resembles closely Gastriaceras, but it already has the 

 Tropites keel before the ventral lobe is divided. But it is quite likely that some of 

 the genera assigned to the Tropitidse do descend directly from other members of the 

 Glyphioceratidffi. 



All s])ecirnens of (TOiilatites crenistria figured in this paper, except those 



on PI. X, figs. 12-16, are deposited iu the geologic collection of Leland 



Stanford Junior University, California, and came from the St. Louis-Chester 



stage (Fayetteville shale), of Moorefield, Ark. Those figured on PI. X, 



figs. 12-1(), are from the Lower Carboniferous, St. Louis-Chester, Bend 



formation, near Richland Springs, San Saba County, Tex. 



Goniatites greencastlensis Miller and Gurley. 



PI. XVII, figs. 12-14. 



1S96. Goniafiti-K (/reencastlcnsis, Miller and Gurley, Bull. Illinois State Mus. Nat. 

 Hist. No. 11, p. 41, pi. 5, rigs. 12-14. 



This species has been referred by E. Hang" to Goniatites s. str., on the 

 supposition that the pointed undivided abdominal lobe was merely tlie lobe 

 of the internal part of the next outer coil pressed on the shell. Tln-ough 

 the kindness of Dr. Stuart Weller the writer was allowed to examine the 

 type of this species in the paleontologic collection, Walker Museum, Univer- 

 sity of Chicago, and found the facts to be as Haug suspected. This 

 specimen is, therefore, a member of Goniatites s. str., and not of Prionoceras, 

 as one would think from the drawing published. 



Occurrence. — Lower Carboniferous, St. Louis stage, Greencastle, Ind. 



afitudes sur les Goniatites, p. 64. 



