2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 



Spence shale fauna occurs in the l)ase o£ the Ute formation in Black- 

 smith Fork. Deiss (1938) remeasured this section, which forms the 

 standard . for the northern Wasatch region, and concluded that the 

 Spence was not present in Blacksmith Fork. But these studies indi- 

 cate that Walcott's original assignment was probably correct. In the 

 Wasatch proper Spence shale fossils were obtained from Two Mile 

 Canyon, near the northern terminus of the range, and from a belt 

 of unknown extent several miles north of Brigham. 



At the latter locality the fauna is found in more calcareous shales 

 than elsewhere. Usually, the Spence shale is a rather soft argillaceous 

 shale, but the fossils are never completely flattened. It seems that 

 fossiliferous lime nodules occur at most localities; at some places 

 these are small, very hard pyritiferous concretions, and at others they 

 consist of crystalline limestone. Irregular oolitic limestone layers 

 are also evidently developed locally. 



Shortly after the large collections were made from Spence Gulch 

 in 1906, illustrations of the more conspicuous elements of the fauna 

 were prepared. The 19 12 monograph includes the brachiopods, and 

 from time to time trilobite species were described incidentally in 

 other papers. Even the present paper does not describe every species, 

 but it gives a fairly accurate concept of the fauna, only a few obscure 

 forms remaining. Neither are the large number of embryonic speci- 

 mens considered. 



The strata in the Pend Oreille Lake region (Resser, 1938) are 

 the only precise equivalents of the Spence shale. Close affinities exist 

 southward in the Wasatch and southwestward from and including 

 the Ophir shale of the Oquirrh Range. Exact correlations are not 

 attempted until several other faunas have been studied. 



In order to save many repetitions of locality descriptions, they are 

 placed here in full, and reference is made to them in the text by 

 number only. 



Locality 5f,c. — Middle Cambrian, Spence shale ; about 5 miles 

 southwest of Liberty, 15 miles west of Montpelier, Bear River Range, 

 Idaho. 



Locality J4L. — Middle Cambrian, Spence shale; Blacksmith Fork, 

 about 10 miles east of Hyrum, Bear River Range, Utah. 



Locality 55^'. — Middle Cambrian, Spence shale; mouth of first 

 small canyon south of Wasatch Canyon, east of Lakeview Ranch, 

 4| miles north of Brigham, Wasatch Mountains, Utah. 



Locality 2o.v. — Middle Cambrian, "Langston," Spence, Ute ; near 

 top of gulch, about 2 miles north of Brigham City, Wasatch Moun- 

 tains, Utah. 



