PLATE XII Continued. 



Paga 

 DlCELLOCEPHALUS FINALI8 -. 89 



Fig. 12. View of the central portions of the head. Natural size. 

 12 a. Associated pygidium, enlarged to two diameters. 

 22. Portion of a thoracic segment on the same fragment of rock. 



AMPHION NEVADENSIS 94 



Fig. 13. View of the portions of the head preserved in the type specime. Natural size. 

 14. Pygidium of unknown generic and specific relations, occurring in association witi. 

 Asaphus Caribouensis, enlarged to three diameters. 



ASAPHUS ? CUBIOSUS I 98 



Fig. 15. Pygidium associated with Asaphus Caribouensis, enlarged to two diameters. 



SYMPHYSTJRUS f GOLDFUSSI 95 



Fig. 16. View of the glabella and portions of the fixed cheeks, enlarged to two diameters. 



CERAURUS ? 95 



Fig. 17. Glabella enlarged to three diameters, to show the granulose surface. 



PTYCHOPARIA (?) ANNECTANS 91 



Fig. 18. Glabella and fixed cheeks, enlarged to two diameters. 



AMPYX ? 00 



Fig. 19. Pygidinm associated with the preceding, and also figs. 7 and 12, enlarged to two 

 diameters. 



ASAPHUS 00 



Fig. 20. Strongly convex pygidium, associated with Asaphus Caribouetisis. 



COLEOPRION MINUTA-- 85 



Fig. 21. Enlargement of a portion of the tube to four diameters, to show the arching of 

 the striae over the longitudinal ridge on the side opposite the arc of curvature. 

 See plate xi, figs. 17, 17 a. 



