350 Canadian Record of Science. 



irregularity in structure does not extend to the allanite. 

 The latter has the appearance of a primary mineral, around 

 which the epidote would naturally tend to crystalize, if any 

 were developed in the rock, the two minerals being 

 isomorphous. 



As it was necessary to carry as little weight as possible 

 over the long stretches of country traversed by the Yukon 

 expedition, only single hand specimens of each rock were 

 collected, and the description given above is that of the 

 single specimen of this Wrangell granite collected by the 

 party. The only other specimen which I could obtain 

 from Fort Wrangell was one kindly given to me by Mr. E, 

 G. McConnell of the Geological Survey of Canada, which was 

 collected by him from the slopes of the hill behind Port 

 Wrangell some years previously, and which proves to be a 

 fine grained Muscovite Granite or Aplite. It occurs associated 

 with the argillites, probably in the form of a dyke. The 

 occurrence of this rock in the vicinity would also point to a 

 probable eruptive origin for the granite above described. 

 The rock is a typical Aplite being composed of quartz, 

 orthocla.se. plagioclase, and a large amount of muscovite. 

 The muscovite is quite normal in its mode of occurrence, 

 and shows no signs of the fretted or indented outline 

 possessed by muscovite in the Pelly Eiver granite to be 

 described further on. It occasionally holds little bunches 

 of black rutile needles, sometimes geniculated twins, and 

 associated with these in the muscovite, a few stout little 

 crystals were observed having a very high index of refrac- 

 tion and well defined crystalline form — acute double pyra- 

 mids truncated by basal planes. These are probably an- 

 atase. A few grains of topaz are also present. 



Granite from Pelly River, Yukon District. — The second 

 rock, unlike that just described, was collected in the interior 

 of the Yukon District, being found on the upper Pelly 

 Eiver near to its confluence with the Lewes Eiver. The 

 specimen is marked "61," the exact point from which 

 it was taken being indicated on Dr. G. M. Dawson's " Map 

 of the Yukon District and British Columbia," Sheet 3. 



