NO. 8 SARDINIAN CAMBRIAN GENUS OLENOPSIS 249 



DESCRIPTION OF PLATE 2,6 (Continued) 



PAGE 



Olenopsis americanus Walcott 243 



Figs. 8. and 9. (Natural size.) Two cranidia that preserve a little of 

 their original convexity. The glabella in both is slightly 

 distorted by compression. U. S. National Museum, Cata- 

 logue Nos. 58368 and 58369, respectively. 



10. (Natural size.) A fragmentary specimen, showing the 



greater part of the thorax. U. S. National Museum, Cata- 

 logue No. 58370. 



11. (X4.) Enlargement of the outer surface as shown in the 



matrix of the specimen represented by figure 10. U. S. 

 National Museum, Catalogue No. 58371. 



All of the specimens illustrating this species are from locality 

 (4v) Lower Cambrian ; about 200 feet above the unconformable 

 base of the Cambrian and 75 feet above the top of the quartzitic 

 sandstones in a shale which corresponds in stratigraphic position to 

 shale No. 6 of the Dearborn River section [Walcott, Smithsonian 

 Misc. Coll., Vol. 53, No. 5, 1908, p. 202], Gordon Creek, 6 miles 

 (9.6 km.) from the South Fork of Flathead River, Ovando quad- 

 rangle (U. S. Geol. Survey), Powell County, Montana. 



