130 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



DESCRIPTION OF PLATE 15 



PAGE 



Elrathia kingii ( Meek) 87 



Fig. I. (Natural size.) A large dorsal shield, somewhat crushed. U. S. 

 Nat. Mus., Cat. No. iS43ga. 



2. (X 2.) A smaller, less distorted specimen with right free cheek 



displaced. U. S. Nat. Mus., Cat. No. I5439h. 



3. (X2.) A fine specimen without the free cheeks. U. S. Nat. 



Mus., Cat. No. 15439c. 



4. (X2.) A small individual. U. S. Nat. Mus., Cat. No. iS439d. 



Matrix, argillaceous shale. Specimens thickened by development 

 of fibrous calcite or aragonite. 



Middle Cambrian, Wheeler formation. (Loc. 4) : Antelope 

 Springs, Plouse Range, Utah. 



Crusoia ccbcs Walcott 82 



Fig. S. (X2.) A small specimen without free cheeks and the pleura 

 on the right side. U. S. Nat. Mus., Cat. No. 70232. 



6. (X2.) Large individual preserving the left free cheek. Tail 



bent under the body. U. S. Nat. Mus., Cat. No. 70233. 



7. (X2.) Cranidium showing the up-turned front and general 



proportions. Glabella slightly flattened. U. S. Nat. Mus., 

 Cat. No. 70234. 



Matrix, soft olive shale. 



Middle Cambrian, Wolsey shale. (Loc. 4g) : 5 miles (8 km.) 

 northeast of Logan, Montana. 



Amecephaliis piochensis (Walcott) 66 



Fig. 8. (Natural size.) Large cranidium. U. S. Nat. Mus., Cat. No. 

 15434a. 



9. (Natural size.) Entire individual. U. S. Nat. Mus., Cat. No. 



I5434b._ 



10. (Natural size.) Smaller but less distorted cranidium. U. S. 



Nat. Mus., Cat. No. 15434c. 



Matrix, pink or bufif calcareous shale. Fossils not completely flat- 

 tened. 



Middle Cambrian, Chisholm formation. (Loc. 31) : Pioche, 

 Nevada. 



Utia curio Walcott 119' 



Fic.s. II, 12. (X 2.) Dorsal view and side outline of a cranidium, illus- 

 trating the steep front, wide fixed cheeks with their pecu- 

 liar grooves and the other characters of this species. U. S. 

 Nat. Mus., Cat. No. 70235. 



13. (X2.) Another cranidium. U. S. Nat. Mus., Cat. No. 70236. 



14. (X 2.) Cranidium with portion of thorax attached. U. S. 



Nat. Mus., Cat. No. 70237. 



Matrix, soft brown shale. Fossils not flattened. 

 Middle Cambrian, Spence shale member of Ute formation. (Loc. 

 55c) : Spence Gulch, 15 miles (24 km.) west of Montpelier, Idaho. 



Bowmania americana (Walcott) y^ 



Figs. IS, 16. (X 2.) Dorsal view and side outline of the type cra- 

 nidium. U. S. Nat. Mus., Cat. No. 24560. 



Matrix, gray limestone. 



Upper Cambrian, Hamburg limestone? (Loc. 66) : Eureka Dis- 

 trict, Nevada. 



