ILLUSTRATIONS. 



I'age. 

 Plate I. Phylogenic table of the Paleozoic ainiuonoids 22 



' II. Phylogenic table of Glyphioceratiila- 58 



III. Figs. 1, 2, Schistoceras hildrethi Morton; figs. 3-13, ShumardUes simondsi Smith 154 



IV. Fig.?. 1-3, Gonioloboc.erax goniolohum Meek; figs. 4-8, Gastrioceras kingi Hall and 



Whitfield; figs. 9-11, Paralegoceras haylorenae White; figs. 12-14, Paralegocerns 



ioivoue Meek and Worthen 156 



"V. Figs. 1 and 2, Prionoceras f hroumense Miller; figs. 3 and 4, Muensteroceras f indianeiise 

 Miller; figs. 5-7, Prolecanites f compactus Meek and Worthen; figs. 8-10, Gaslriocerax 



nolinense Cox; fig. 11, Nomismoceras ? monroense Worthen 158 



VI. Fig. 1, Gastrioceras globidosum Meek and Worthen; figs. 2-5, Goniatites limatus Miller 

 and Gurley; figs. 6-8, Prolecanites louisianensis Rowley; figs. 9-11, Bactrites car- 



bonarius Smith 160 



VII. Agoniaiites opimus White and Whitfield 162 



VIII. Fig. 1, ScJiistoceras missourieiue Miller and Faber; figs. 2 and 3, Aganides ? sciotoensis 

 Miller and Faber; figs. 4 and 5, Prolecanites greenii Miller; figs. 6 and 7, Gastrioceras 

 occidentale Miller and Faber; figs. 8 and 9, Gonioloboceras ? limalum Miller and 



Faber; figs. 10 and 11, Glyphioceras lenculum Miller and Faber 164 



IX. Figs. 1-3, Gastrioceras compressum Hyatt; figs. 4-7, Paralegoceras iowense Meek and 



Worthen 166 



X. Figs. 1-11, Goniatites strialus Sowerljy; figs. 12-16, Goniatites crcnistria Phillips; figs. 



17-19, Gastrioceras entogonum Gabb 168 



XI. Figs. 1-4, Gastrioceras carbonarium von Buch; figs. 5-7, Pronorit.es siebenthali Smith; 



figs. 8-13, Gastrioceras branneri Smith 170 



* XII. Figs. 1 and 2, Pronorites prxpermieus Karpinsky; fig. 3, Pronorites cyclolobus Phillips; 

 figs. 4^9, Paralegoceras newsomi Smith; flg. 10, Glifphioceras diadema Goldfuss; fig. 

 11, Tornoceras retrorsum von Buch; figs. 12-15, Pronorites cyclolobus Phillips var. 



<irkansasensis Smith 172 



' XIII. Figs. 1-5, Pronorites c,(/(io/o6ta Phillips; figs. 6-15, Gastrioceras listeri Ma.rtin 174 



XIV. Goniatites crenistria Phillips, larval stages 176 



XV. Goniatites crenistria Phillips, development from adolescence to maturity 178 



XVI. Fig. 1, Goniatites crenistrin Phillips, development of the septa; fig. 2, Gastrioceras e.rcelsinn 

 Meek; fig. 3, Muensteroceras parallehun Hall; figs. 4-5, Pericyclus blairi Miller and 

 Gurley; figs. 6-8, MilUroceras parrishi Miller and Gurley; figs. 9-11, Xeoicoceras 

 elkhornense Miller and Gurley; figs. 12-14, Gastrioceras montgomeryense Miller and 

 Gurley; figs. 15-17, Schistoceras fultonense Miller and Gurley; fig. 18, Prolecanites 

 lyoni Meek and Worthen; fig. 19, Aganides rotatorius de Koninck; tig. 20, Pericyclus 

 kochi Holzapfel; fig. 21, Popaimcerns parkeri Heil]irin 180 



