138 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



DESCRIPTION OF PLATE 19 



PAGE 



Idahoia serapio Walcott 96 



Figs. I, 2. (Natural size.) Dorsal and side views of an almost com- 

 plete cranidium. Outlines restored. U. S. Nat. Mus., Cat. 

 No. 70289. 



3. (Natural size.) Broken and distorted cranidium but with the 

 occipital spine well preserved. U. S. Nat. Mus., Cat. No. 

 70290. 



4,5. (Natural size.) Associated free cheek and cast from mould 

 of same, preserving the general characters. U. S. Nat. Mus., 

 Cat. Nos. 70291, 70292. 



6. (Natural size.) Portion of large, free cheek with genal spines. 



U. S. Nat. Mus., Cat. No. 70293. 



7. (Natural size.) Cast of the outer portion of a free cheek pre- 



serving several small patches of test. Note the striations on 

 the rim. U. S. Nat. Mus., Cat. No. 70294. 



8. (Natural size.) Smaller free cheek showing outer surface. 



U. S. Nat. Mus., Cat. No. 70295. 



9. ID. (Natural size.) Associated hypostoma referred to the spe- 



cies. U. S. Nat. Mus., Cat. No. 70296. 



11. (Natural size.) Pygidium somewhat doubtfully referred to 



this species. U. S. Nat. Mns., Cat. No. 70297. 



12. (Natural size.) Cast of an associated broken pygidium. U. S. 



Nat. Mus., Cat. No. 70298. 



Matrix, limestone. 



Upper Cambrian, Ovid formation. (Locs. S4w, 4y) : Near Malad, 

 Idaho. 



Idahoia nialadensis Walcott 99 



Fig. 13. (Natural size.) Large incomplete cranidium. U. S. Nat. Mus., 

 Cat. No. 70299. 

 14. (Natural size.) Well preserved pygidium referred to the spe- 

 cies. U. S. Nat. Mus., Cat. No. 70300. 



Matrix, limestone. 



Upper Cambrian, Ovid formation. (Loc. 5e) : 2 miles (3.2 km.) 

 southeast of Malad, Idaho. 



