Qeology and Mineralogy. 493 



JSFote " 071 the Youngest Huronian Bocks South of Lake 

 " ' "" > Irving. —In a paper with the above title 



number of this Journal, Mr. T. B. ; 

 by an accidental misquotation, makes me responsible for 

 composed of a strange medley of minerals. He says that I men- 

 tion " these rocks as being coarsely crystalline aggregates ' chiefly 

 of labradorite and orthoclase feldspar, hornblende and some variety 

 of pyroxene.' " I wrote,* " Nearly all of them can, however, be 

 included in two or three general kinds, labradorite, orthoclase fel- 

 spar, hornblende and some variety of pyroxene seeming to be the 

 chief ingredients." In this I meant to mention the main ingre- 

 dients of the different kinds, not to say that all of these minerals 

 occur in one rock. I am inclined, with my present knowledge, to 

 follow Mr. Brooks in referring to the Huronian the belt of rocks 

 in Northern Wisconsin, to which the above quotation alludes, as 

 I followed him before in referring them to the Copper Series.f I 

 cannot agree with him in designating the rocks as "granitoid," 

 as, so far as ray knowledge goes, they are chiefli^ rocks of a low 

 degree of silication consisting mainly of labradorite and pyroxene. 

 The general run of the rock in the country occupied by this belt 

 west of Bad River is a dark colored coarsely crystalline mixture 

 lompanied by hypersthent 

 ascertained recently by I 

 Wright from a microscopic examination made by him for me. 

 The " granitoid " rocks which Mr. Brooks has seen occur as 

 patches among these dark colored diabases and allied rocks. In 

 the former only have I noticed orthoclase and hornblende. 

 University of Wisconsin, April 27tli, 1816. 



5. Gigantic fossil bird from the Eocene of New Mexico ; 

 Prof. Cope. (Proc. Acad. N. Sci. Philad., 1876.)— This bird was 

 related both to the Cursores (Struthionidae and Dinornis) and to 

 Gastornis of the Paris basin. Its size was twice that of the 

 ostrich. Prof. Cope names it Diatryma gigantea. 



6. JRichmond Infusorial Stratum. — Mr. Charles Stodder in a 

 the Richmond Infusorial stratum, first described l)y 

 W, B. Rogers in his Virginia Report of 1840, (tliis 



Journal, xlv, 313, 1843), states that Mr. R. B. Tolles examined 



Shockoe Hill, near Richmond, and obtained specimens at the 

 <3epths, 5, 71, 10, 11, and 14 feet below the top of the bank, and 

 and also from the north side 40 feet below the top, from a bed 

 which was apparently a continuation of the 14-feet bed, the hill 

 ^eing higher on the north side. The lower layer contains 50 to 80 

 per cent of organic forms, the uppermost about 20 per cent. The 

 species below this top layer vary but little ; while in that they 

 are partly different in species, and the frustules are less broken. 

 * See paper " On the Age of the Copper-Bearing Rocks of Lake Superior, this 



ffi 



