24-6 F. M. Kindle — Notes on Devonian Faunas. 



Art. XXVII. — Notes on Devonian Faunas of the MacKenzie 

 River Valley ; by E. M. Kindle. 



The Devonian rocks east of the MacKenzie valley are 

 bordered for nearly a tbonsand miles by the Pre-Cambrian 

 rocks of the Canadian shield."' The geological map of North 

 America, published through the cooperation of the geological 

 surveys of the United States, Canada, and Mexico,f indicate 

 the termination of the broad belt of the MacKenzie valley 

 Devonian on the north by a western lobe of the Pre-Cambrian 

 rocks which, in the region east of the delta of the MacKenzie, 

 are bordered by the Cretaceous formations according to this 

 map. 



A coral collected by H. W. Jones and transmitted to me by 

 Mr. Chas. Camsell furnishes evidence of the presence of 

 Devonian Rocks, in this very northerly region east of the 

 delta of the MacKenzie within 70 miles of the Arctic coast, 

 where published data show only Cretaceous and Pre-Cambrian 

 terraines. The specimen collected by Mr. Jones was obtained 

 on the east side of Gull Lake from the limestone shown in 

 fig. 1. The photograph shows a limestone section with a thick- 

 ness of more than 100 feet in which the beds lie nearly hori- 

 zontal. The Gull Lake district is one which does not appear 

 to have been traversed by geologists. The geography of the 

 district was described by A. H. Harrison in 19084 Gull Lake 

 is probably Long Lake of Harrison's map or one of the small 

 lakes near Long Lake. Long Lake is the most westerly of a 

 chain of lakes lying east of the delta and trending a little east 

 of north through a region lying, according to Harrison's map, 

 between 100 and 500 feet above the sea. 



The corallites of the specimen on which the determination of 

 this new occurrence of Devonian rocks is based are partially 

 silicified and imbedded in an impure grey limestone. The 

 coral belongs to the species Aeervularia davidsoni E. <fe H. 

 It represents the variety of this species described by Hall from 

 the Iowa Devonian as A. profunda. The variable character 

 of the size of the corallites ascribed to A. profunda is well 

 illustrated by this specimen, the smaller ones having no more 

 than half the diameter of the larger ones. Most of the cells 

 have 40 or more radial denticulated lamellae. In this identifi- 

 cation I have followed Rominger in treating Hall's A. pro- 

 funda as a synonym of A. davidsoni. 



* MeConneil. E. G., Ann. Eept. Geol. Surv. Can., n. ser., vol. 4, 1890, p. 

 14D. 



+ U. S. Geol. Surv., Prof. Paper 71, 1911. 



X A. H. Harrison, In Search of a Polar Continent, pp. 1-292, map (E. 

 Arnold), London, 1908. Idem, In Search of an Arctic Continent, London 

 Geog. Jour. vol. xxxi, pp. 277-287, map, 1909. 



