BROOKSINA, A NEW PENTAMEROID GENUS FROM THE 

 UPPER SILURIAN OF SOUTHEASTERN ALASKA. 



By Edwin Kirk, 

 Of the United States Geological Siinjei/. 



The stratigrapliy and paleontologic content of the Paleozoic rocks 

 of southeastern Alaska are perhaps less known than those of any other 

 notable Paleozoic section in North America, Fairly extensive col- 

 lections of fossils are now available from this region. Of consid- 

 erable importance in southeastern Alaska is a great series of sediments 

 of doubtful stratigraphic position. Within this series are contained 

 some 3,500 feet of limestone, shales of unknown thickness, and more 

 than 1,000 feet of conglomeratic beds considered ^ as of probable 

 glacial origin. Compared with other North American faunas the 

 fossils of this series bear some resemblance to the Upper Monroe 

 of Michigan. The affinities are not close, however, and consist mainly 

 in the common possession of persistent generic types. It should be 

 borne in mind that the greater part of the Alaskan Paleozoic faunas 

 are Asiatic and European in their affinities, and correlations should 

 be sought there rather than elsewhere in North America. The faunas 

 we are now considering appear closely related to the Lower Devonian 

 of the Ural Mountains as described and discussed by Tschernyschew.^ 

 L'ntil such time as more accurate correlations of these sediments of 

 the Urals shall have been made with the European standard and the 

 Silurian-Devonian boundar3^ itself shall have been more definitely 

 fixed in Europe the age of the Alaskan sediments must remain in 

 doubt. 



My personal inclination is toward the assignment of this Alaskan 

 series to the Devonian. However, owing to the Silurian aspect of 

 the faunas as compared with faunas elsewhere in America, and to 

 the fact that certain of the sedimentary units have already appeared 

 in the literature as of Silurian age it has seemed best tentatively 

 to assign the beds to the Upper Silurian. In any event we probably 

 have to deal with a time period unrepresented elsewhere in North 



^ Kirk, Edwiii, Paleozoic glaciation in soutlieasfern Alaska, Amor. .Toiun. Sci., vol. 46, 

 pp. ."511-515, Sept., 1918. 



- Tschcrnyscliew, Tli., IMe Fauna des Untern Devon am West-Abhange des Urals, M4m. 

 Comite Gfeol., vol. 3, No. 1. 



Beachreibung des Central-Urals und des West abhanges, Mem. Comity G6ol., vol. 3, No. 4. 



No. 2414— Proceedings U. S. National Museum, Vol. 60, Art. 19. 



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