PLATE IV. 



PAGB. 



Plumulites Jamesi 106 



Figs. 1 aud 2 represent detached plates of the species from Cincinnati, Ohio, greatly enlarged. 



Fig. 3. An outline tracing of a figure of a very perfect specimen, natural size, given by Henry 

 "Woodward, Esq. (Quar. Jour. G-eol. Soc, Vol. XXI., plate 14, fig. Ih.) Introduced here 

 for comparison, and to show the structure and arrangement of the plates. 



LePERDITIA (IsOCHILINA) MINUTISSIMA 102 



Fig. 4. View of a left valve of the species, greatly enlarged. 



Leperditia (Isochilina) cylindrica 101 



Fig. 5. View of a right valve, greatly enlarged. 



Beyrichia quadbilirata 105 



Fig. 6. View of a left valve, showing the character of the ridges and sulci. 

 7. A basal profile in oatline, showing the valves in conjunction. 



Beyrichia tumifrons 102 



Fig. 8. View of a left valve, enlarged. i, 



Beyrichia oculifera 103 



Fig. 9. I^^teral view of a specimen, showing the sulci and the character of the eye tubercle. 

 10. Basal profile view, showing the elevation of the tubercle. 



Beyrichia Chambersi 104 



Fig. 11. A partial profile view of a left valve, showing the length of the spine, which does not appear 

 to be seiTated, and also the depth of the sulci. 

 12. Lateral view of a right valve, showing the character of the species. 



Calymene Ghristyi 107 



Figs. 13 and 14. Vertical and profile views of the original specimen from which the species was 



described. * 



Fig. 15. Outline view of a pygidimn. 



DaLMANIA BREVICEP8 108 



Fig. 16. View of the original specimen. 



17. Oatline profile of the same specimen. 



Pboetus parviusculus 109 



Fig. 18. View of the type specimen, enlarged to four diameters. 



Orthoceras Carleyi 98 



Fig. 19- View of the specimen described, showing the several tubes referred to, and their positions 

 in relation to each other. 



