PLATE IV. 



PAGE. 



Plumulites Jamesi , 106 



rigs. 1 and 2 represent deta< bed plates of the species from Ci cinnati, Ohio, greatly enlaijied. 



Fig. .3. An outline tiacing of a tigure of a very perfect siieoinun, natural size, given b\ Henry 

 Woodward, Jisq. (Quar. Jour. Geol. Si'ic, Vol. XXL, plate 14, tig. l/(.) Introduced here 

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



Lepeeditia (Isochilina) minutissima 102 



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



Leperditia (Lsochilina) cylixdkica 101 



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



BeYKICIIIA (iUADRILIRATA 105 



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

 7. A basal protile iu outline, showing the valves in conjunction. 



Beyrichia tumifrons 102 



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



Beyrichia ocilifera 108 



Fig. 9. Lateral view of a specimen, showing the sulci and the character of the eye tubercle. 

 10. Basal piofile view, showing the elevati'ou of the tubercle. 



Beyrichia Chambersi 104 



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

 to be serrated, and al.so the depth of the sulci. 

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



Calymene Christyi 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 pygidium. 



Dalmania breviceps 108 



Fig. Ifi. View of the original specimen. 



17. Outline profile of the same specimen. 



Proetus parviusculus 109 



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



Oi:tii()Ceras Cakleyi 98 



Fig. 19, View of the specimen dcscrilied, showing the several tubes referred to, and their po.sitions 

 in relation to each other. 



