218 GRANITES AND GRANITIC VEIN-STONES. [XL 



generally described as occurring in crystalline limestones, 

 though C. U. Shepard, H. D. Rogers, and W. P. Blake have 

 each recognized the fact that these mineral species, with their 

 calcareous gangue, belong to true veins. Emmons, however, 

 failed to distinguish between these vein-stones arid the stratified 

 limestones of the series, which, as already stated, often contain 

 disseminated many of the same species, though in a less per- 

 fectly crystallized condition than in the vein-stones. Since the 

 latter are clearly seen to traverse the gneiss, like dikes, Emmons 

 was led to look upon them as eruptive ; and, generalizing from 

 this, he declared that all the crystalline limestones of northern 

 New York were non-stratified rocks of eruptive origin. (Geology 

 of the First District of New York, 1842, pages 37 - 59.) This 

 view of Emmons was, to a certain extent, adopted by Mather, 

 who, while maintaining the stratified character of the crystalline 

 limestones of southern New York, admitted the existence of 

 eruptive limestones. Von Leonhard had already, in 1833, 

 asserted that limestones have sometimes come from the interior 

 of the earth in a liquid state, like other igneous rocks, and a 

 similar view was at that time maintained by many other 

 geologists. Among others we find Rozet asserting the eruptive 

 origin of the crystalline limestones which are associated with 

 gneiss in the mountains of the Vosges. (Bull. Soc. Geol. de 

 France, III. 215 - 235.) In support of this view could be 

 urged the dike-like form of the calcareous vein-stones, which 

 other observers, like Emmons, confounded with the bedded 

 limestones. The nature and origin of this misconception were, 

 I believe, first pointed out by me in a communication to the 

 American Association for the Advancement of Science in Au- 

 gust, 1866 (Canadian Naturalist (2), III. 123), and subse- 

 quently more at length in the essay so often referred to. (Report 

 Geol. Survey of Canada, 1863-66, p. 182.) It was there 

 shown that many of these calcareous vein-stones are nearly free 

 from foreign minerals, and so closely resemble in lithological 

 characters the stratified limestones, that the different geognosti- 

 * cal relations of the two alone enable us, in some examples, to 

 distinguish between them. In this connection I called atten- 



