PALEOZOIC ROCKS, LISBURNE FORMATION. 65 



The fossils from the Lisburne formation collected by the writer have been 

 identified by Mr. Charles Schuchert as follows: 



Fossils of the Lisburne formation. 

 Locality 455. 

 Produetella (2 species). 

 Platystoma. 

 Zaphrentis. 

 Fenestella. 

 Unitrypa. 



Eridotrypa, nearly identical with E. barrandei (Nicholson) of the Middle Devonian. 

 Localities 460 and 462. 



Spirifer disjunctus. 

 Localities 496, 498, 499, 501, 523, and 524. 



Diphyphylluni (1 species). 

 Locality 500. 

 Zaphrentis. 

 Locality 528. 



Aulocophyllurn. 

 Locality 533. 

 Zaphrentis. 

 Rhombopora. 

 Fenestella. 

 Hemitrypa. 

 Localities 455 and 528 appear to be of one formation of the Middle Devonian. The species present 

 suggest very much the Athabasca-Mackenzie Middle Devonian, collected many years ago by Kennicott 

 and described by Meek in the Transactions of the Chicago Academy of Sciences. 

 Localities 460 and 462. 

 Spirifer disjunctus, one of the fossils characterizing the Upper Devonian. The same species is 

 also found in the Peace, Hay, and Liard River regions of Arctic Canada. 

 Localities 496, 498, 499, 501, 523, and 524. 

 Diphyphylluni (1 species). This genus extends in America from the Upper Silurian to the 

 close of the Middle Devonian, and will probably also be found in the Upper Devonian, so that, 

 unsupported by other evidence, it does not indicate an exact horizon. This or a very similar 

 species has been found at or near the mouth of Mackenzie River in Devonian rocks. 

 Localities 500 and 533 are probably also of Devonian age. 



Correlation. — On lithologic grounds it appears that the Lisburne formation can 

 safely be correlated with the medium-bedded, unsheared limestone portion of the 

 Bettles series, which is best exposed near the mouth of Bettles River, on the 

 Koyukuk, a and it probably continues to the head of Chandlar River. Thus this 

 limestone formation extends from the region west of the Anaktuvuk eastward 100 or 

 more miles, and the presence of Devonian still farther eastward, to the north of the 

 Chandlar, is rendered highly probable by a few fossils collected from the Chandlar 

 River gravels in 1899 by the writer.* These fossils, a list of which follows, were 

 identified by Dr. George H. Girty, whose statements thereon are here inserted. 



aSehrader, F. C, Reconnaissance along the Chandlar and Koyukuk rivers, Alaska: Twenty-first Ann. Rept. U. S. 

 Geol. Survey, pt. 2, 1900, p. 475. 

 b Ibid. 



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