NO. 3 CAMBRIAN AND OZARKIAN TRILOBITES 143 



DESCRIPTION OF PLATE 23 



PAGE 



Belief ontia collieana (Raymond) Ulrich 72 



Figs. 1,2. (X 2.) Dorsal and side views of a small but fairly com- 

 plete cranidium. U. S. Nat. Mus., Cat. No. 70341. 



3. (X 2.) Dorsal view of a less complete head. U. S. Nat. Mus., 



Cat. No. 70342. 



4. (X2.) A small, partly exfoliated free cheek. U. S. Nat. Mus., 



Cat. No. 70343. 

 5,6. (Natural size.) Dorsal and side views of an associated py- 

 ffidium, from which the test has been exfoliated. U. S. Nat. 

 Mus., Cat. No. 70344. 



Matrix, limestone. 



Canadian, Lower Stonehenge. (Log. 27ir) : Bellefonte, Pennsyl- 

 vania. 



Belief ontia nonius Walcott 72 



Fig. 7. (Natural size.) Cranidium with outlines restored. U. S. Nat. 

 Mus., Cat. No. 70345. 



8. (Natural size.) Small head. U. S. Nat. Mus., Cat. No. 70346. 



9. (Natural size.) Free check found in association with this form. 



U. S. Nat. Mus., Cat. No. 70347. 

 10, II. (Natural size.) Pygidia showing the characters of the spe- 

 cies. U. S. Nat. Mus., Cat. Nos. 70348, 70349. 



Matrix, limestone. , 



Ozarkian, Mons formation. (Loc. 6-,y) : North side of Clear- 

 water Canyon, 2 miles (3.2 km.) from divide at head of canyon and 

 about 21 miles (33.8 km.) in an air line north, 2° west, of Lake 

 Louise Station, on the Canadian Pacific Railway, Alberta, Canada. 



Leiostegium manitouensis Walcott 104 



Figs. 12-14. (Natural size.) Dorsal, side, and front views of a fairly 

 complete cranidium illustrating the generic and specific char- 

 acters. U. S. Nat. Mus., Cat. No. 70350. 



15. (Natural size.) Free cheek. Rim broken away, exposing the 



doublure for most of the distance. U. S. Nat. Mus., Cat. 

 No. 70351. 



16. (Natural size.) Dorsal view of an associated pygidium. LT. S. 



Nat. Mus., Cat. No. 70352. 



17. (Natural size.) Dorsal view of a well preserved associated 



pygidium. U. S. Nat. Mus., Cat. No. 70353. 



18. (Natural size.) Small, slightly distorted cranidium. LT. S. 



Nat. Mus., Cat. No. 70818. 



19. (Natural size.) Pygidium preserving most of the test. U. S. 



Nat. Mus., Cat. No. 70817. 



Matrix, red siliceous limestone. 



Ozarkian (A'Tanitnu limestone). (Loc. 187) : Manitou Park, Colo- 

 rado. Ozarkian (Chushina formation). (Loc. 6iq) : Billings Butte, 

 east, near base of Robson Peak, British Columbia. 



Moosia grandis Walcott 107 



Fig. 20. (Natural size.) A large cran'dium somewhat distorted, illus- 

 trating the characters of the species. U. S. Nat. Mus., Cat. 

 No. 70355. 

 21. (Natural size.) Pygidium associated and referred to this spe- 

 cies. U. S. Nat. Mus., Cat. No. 70356. 



Matrix, siliceous shale. 



Upper Cambrian, Goodsir formation. Moose Creek, British Co- 

 lumbia. 



