NO. 3 CAMBRIAN AND OZARKIAN TRILOBITES 145 



PAGE 



Xenostegium schofieldi Walcott 127 



Fig. 15. (Natural size.) Tj^pe pygidium. U. S. Nat. Mus., Cat. No. 

 70366. 

 Matrix, limestone. 



Ozarkian, Mons formation. North end of Swansea Mountain, 

 north-northeast of Lake Winderrnere, British Columbia, Canada. 



Xenostegium shepardi (Raymond) -. 128 



Fig. 16. (Natural size.) Dorsal view of an excellent pyg'dium. U. S. 

 Nat. Mus., Cat. No. 70367. 

 Matrix, limestone. 



Ozarkian, Mons formation. (Loc. 66u) : Above Mons Glacier, 

 Glacier Creek District, Alberta, Canada. 



Fig. 17. (Natural size.) Cast of Raymond's type. U. S. Nat. Mus., • 

 Cat. No. 70368. 

 Matrix, limestone. 



Ozarkian. Mons formation, Sinclair Canyon, British Columbia, 

 Canada. 



Xenostegium kirki Walcott 127 



Fig. 18. (Natural size.) Several cranidia and pygidia. U. S. Nat. 

 Mus., Cat. No. 71369. 

 19. (Natural size.) Posterior portion of a pygidium. U. S. Nat. 

 Mus., Cat. No. 71370. 

 Matrix,, limestone. 



Ozarkian, Mons formation. (Loc i/o) : North of Stoddart Creek 

 Canyon, Stanford Range, British Columbia, Canada. 



Fig. 20. (Natural size.) Partially exfoliated cranidium doubtfully re- 

 ferred to this species. U. S. Nat. Mus., Cat. No. 70371. 

 21. (Natural size.) Pygidium, associated with fig. 20. U. S. Nat. 

 Mus., Cat. No. 70372. 

 Matrix, limestone. 



Ozarkian, Mons formation: (Loc. 67q) : Douglas Lake, Canyon 

 Valley, Sawback Range, Alberta, Canada. 



Xenostegiuwi douglasensis Walcott 125 



Fig. 22. (Natural size.) An imperfect cranidium. U. S. Nat. Mus., 

 Cat. No. 70373- 

 2.3. (Natural size.) Associated pygidium. U. S. Nat. Mus., Cat. 

 No. 70374- 

 Matrix, limestone. 



Ozarkian, Mons formation. (Loc. 67q) : Douglas Lake, Canyon 

 Valley, Sawback Range, Alberta, Canada. 



Isoteloides ? sp. undt 100 



Fig. 24. (Natural size.) Fragment of a cranidium. U. S. Nat. Mus., 

 Cat. No. 70375- 

 Matrix, limestone. 



Ozarkian, Mons formation. (Loc. 67h) : 3 miles (4.8 km.) south 

 of Wilcox Pass, Alberta, Canada. 



Isoteloides ? lautus Walcott 99 



Fig. 25. (Natural size.) Cranidium and associated free cheek. U. S. 

 Nat. Mus., Cat. No. 70376. 

 Matrix, limestone. 



Ozarkian, Mons formation. (66v) : Upper Johnson Creek Canyon, 

 Sawback Range, Alberta, Canada. 



