438 THE CANADIAN NATURALIST. [Vol. viii. 



metrically banded arrangement of their ingredients ; the feldspar 

 occupying the sides and jutting out in coarse crystals towards 

 the middle, which is filled with quartz. 



Dr. T. Sterry Hunt has assigned* quite a different mode of 

 formation to the apatite-bearing veins of Canada, which, accord- 

 ing to the description, must be perfectly similar to ours. He 

 distinguishes three different varieties of veins as occurring in the 

 Laurentian formation : 1. Lead-bearing veins, which are said 

 to be much younger than the other two varieties ; 2. Grani- 

 tic veins, which would seem to be comparable to our ordinary 

 coarsely crystalline granitic veins, as Dr. T. S. Hunt has himself 

 pointed out ; 3. Calcareous veins, which are generally associated 

 in their occurrence with the eozoon limestones, w T hich Dr. Hunt 

 considers to be sedimentary. This third group of veins, which 

 is common in Canada, and also sometimes occurs in the northern 

 part of the United States, is usually rich in calcspar, and corres- 

 ponds to our apatite-bearing veins. The similarity is surprising. 



Dr. T. Sterry Hunt tries to explain the formation of the calca- 

 reous veins, as well as the granitic veins already mentioned, by 

 hot solutions charged with the ingredients of the stratified rocks 

 having deposited the dissolved matters in vein fissures ; he terms 

 veins formed in this way "endogenous." He seeks to establish 

 his theory especially upon the fact that almost all the vein- 

 minerals occur also in the stratified country-rock, as well as by 

 the fact that calcareous veins occur especially in the limestone 

 and the granitic veins, especially in the gneiss and micaceous 

 schists. These conditions are not met with in our veins. We 

 are not aware of apatite or any other mineral containing phos- 

 phoric acid having been found in the country rock of the veins. 

 This holds good not only of the phosphatic minerals, but also of 

 rutile and many other minerals occurring in the apatite bearing 

 veins. And in no other respect, although our attention was 

 especially turned to this point, could we observe any definite 

 relation between the minerals of the veins and those of the 

 country-rock. In a rock of such constant composition as gabbro 

 there occur large, almost pure veins of enstatite, veins of mica, 

 segregations of hornblende and mica, veins of apatite, etc. The 

 apatite-bearing veins and the numerous granitic veins occur also 

 side by side in the same rocks. On the other hand, it could be 



* Geology of Canada, 1866, pp. 186-233. 



