132 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



DESCRIPTION OF PLATE 16 



PAGE 



Modocia oweni (Meek and Hayden) 106 



Figs, i, 2. Dorsal and side views of a cranidium in coarse sandstone. 

 U. S. Nat. Mus., Cat. No. '24581. 



Matrix, sandstone. 



Upper Cambrian, Deadwood formation. Castle Creek, Black Hills, 

 South Dakota. 



3. Dorsal view of the type cranidium of the species. U. S. Nat. 

 Mus., Cat. No. 1 180. 



Matrix, fine-grained sandstone. 



Upper Cambrian, Deadwood formation. Head of Powder River, 

 Big tlorn Mountains, Wyoming. 



Dunderbergia nitida (Hall and Whitfield) _. 85 



Fig. 4. Dorsal view of a fairly complete cranidium. U. S. Nat. Mus., 

 Cat. No. 24S72a. 



5. Side view of original type specimen. U. S. Nat. Mus., Cat. No. 



24S72b. _ , . . 



6, 7. Dorsal and side views of pygidium assigned to this species. 



U. S. Nat. Mus., Cat. No. 24S72C. 



Matrix, limestone lenses in shale. 



Upper Cambrian, Secret Canyon shale. (Loc. 61) : Eureka Dis- 

 trict, Nevada. 



Iddingsia similis (Walcott) 97 



Figs. 8, 9. Dorsal and side views of the type cranidium. U. S. Nat. 

 Mus., Cat. No. 24641. 



Matrix, limestone. 



Upper Cambrian, Secret Canyon shale. (Loc. 60) : Eureka Dis- 

 trict, Nevada. 



Iddingsia robusta (Walcott) 97 



Figs. 10, 11. Dorsal and side views of an imperfect cranidium. U. S. 

 Nat. Mus., Cat. No. 24609. 



Matrix, limestone. 



Upper Cambrian, Secret Canyon shale. (Loc. 61) : Eureka District, 

 Nevada. 



Eurekia dissimilis (Walcott) 90 



Fig. 12. Dorsal view of a fragmentary cranidium which is the original 

 type of the species. U. ,S. Nat. Mus., Cat. No. 24615. 



Matrix, limestone. 



Upper Cambrian, Secret Canyon shale. (Loc. 54) : Prospect 

 Mountain, New York Canyon, Eureka District, Nevada. 



Eurekia granulosa Walcott 90 



Fig. 13. A cranidium on which the missing parts have been restored. 

 U. S. Nat. Mus., Cat. No. 70239. 



14. Small cranidium with the front fairly complete, used in the 



restoration of fig. 13. U. S. Nat. Mus., Cat. No. 70240. 



15, 16. Free cheeks. U. S. Nat. Mus., Cat. Nos. 70241, 70242. 



17. Pygidium assigned to this species. Restored in outline on right 

 side. U. S. Nat. Mus., Cat. No. 70243. 



Matrix, granular limestone. 



Upper Cambrian, Hamburg ? formation. (Loc. 88) : West side of 

 Highland Range, 17 miles (27.3 km.) southwest of Pioche, Nevada. 



