etic relations between igneous rocks can properly mark the lines along 

 which a systematic classification of them may be established. 



Petrographical Notes.— In a phyllite-schist found in blocks on 

 the south shore of Lake Michigamme in Michigan, Hobbs 7 has discov- 

 ered large crystals of a chloritoid like that described by Lane, Keller 

 and Sharpless in 1891. The rock in which the crystals occur is a mass 

 of colorless mica scales through which are distributed large flakes of 

 biotite, small blades of chloritoid, a few acicular crystals of tourmaline 

 and grains of magnetite. Most of the chloritoid is in large porphyritic 

 crystals imbedded in this matrix. The optical properties of the mineral 

 correspond to those of masonite. 



In a summary of the results of this work in the upper Odenwald 

 Chelius announces the existence there of two granites— the younger a 

 fine grained aplitic variety and the older a coarse grained porphyritic 

 variety, with a parallel structure due to flowage. Pegmatitic veins 

 that cut this granite are looked upon as linear accumulations of por- 

 phyritic feldspar crystals. Many notes are also given on the diorites, 

 gabbros and basalts of the Odenwald, on the basic enclosures in the 

 granite, which the author regards as altered fragments of foreign basic 

 rocks, but nothing of a startling nature with reference to these subjects 

 is recorded. A gabbro porphyry was found occurring as a dyke mass. 

 It consists of phenocrysts of labradorite in a gabbro-aplitic ground- 

 in a general paper on the divisibility of the Laurentian in the Morin 

 area N. W. of Montreal, Canada, Adams 8 describes the characteristics 

 of the members of the Grenville series of gneisses, quartzites and lime- 

 stones. The augen gneisses, the thinly foliated gneisses and the granu- 

 les of the series are all cataclastic or granulitic in structure. They 

 are regarded as squeezed igneous rocks. The crystalline limestones and 

 quartzites are recrystallized rocks that are thought to be changed sedi- 

 mentaries. Pyroxene gneisses, pyroxene granulites and other allied 

 rocks are of doubtful origin. In addition to all these rocks there is 

 • banded garnetiferous gneisses 



which from their chemical 



T metamorphosed sedimentary rocks. 

 T Amer. Jonr. ScL, Vol. L, 1895, p. 125. 

 8 Amer. Jour. Sci., Vol. L, 1895, p. 58. 



composition are regarded as in all probabil- 



