Explanation of the Plates. 



333 



PLATE HI. 



CONOCEPHALITES MINOR. 



[Figures four times enlarged.] 



Fig. 1. The glabella and fixed cheek. 



" 2. Profile of the same. 



M 3. A movable cheek. 



" 4. A pygidium of the same. 



CONOCEPHALITES MINTJTUS. 



[Figures four times enlarged ] 



Fig. 5. Glabella and fixed cheeks. 

 " 6. Profile of the same. 

 " 7. Cheek of the same species. 



CONOCEPHALITES EOS. 



Fig. 8. Glabella and fixed cheeks. 

 9. Profile of the same. 



CONOCEPHALITES IOWENSIS. 



Fig. 10. A small head. The glabella is represented too round in front. See figure 29, Plate vii. 

 " 10 a. Hypostoma of this species. 

 " 11. A cheek of the same species. 

 " 12. A pygidium of the same. 



Ptychaspis GRANULOSUS ? 



Fig. 13. A pygidium, which is of frequent occurrence in slabs containing the head of this species. 

 " 14. The pygidium of an undetermined trilobite. 



DlKELOCEPHALUS MISA. 



Fig. 15. The glabella and fixed cheeks of this species. The glabellar furrows are not properly 

 copied in this figure. See figure 4 of Plate 5. 



CONOCEPHALITES ERYON. 



Fig. 16. A glabella and fixed cheeks of this species. The glabella is represented too round in 



front. See figure 10, Plate vii. 

 " 31. A similar specimen from Lacrosse. The anterior pair of furrows are rarely seen. 



CONOCEPHALITES OWENI. 



Fig. 17. A glabella and fixed cheeks. 

 " 20. A movable cheek from the same specimen in which the head is found. 



. CONOCEPHALITES DIADEM ATUS. 

 Fig. 18. The glabella and frontal limb of this species showing a very narrow space between the 



former and the elevated portion of the latter. 

 " 21. A pygidium, associated in the same specimens of stone with the glabella: from Marine 

 mills. 



