1885.] Mineralogy and Petrography. 99I 
diluvial age. At that time middle Europe was a land of steppes, 
and a strong-kneed, thick headed, medium-sized wild horse existed 
there. Later on the steppe became covered with forest, the 
moist climate of which was unfavorable to the horse, which be- 
came confined to the pasture grounds and thus fell more and 
more under the influence of domestication, whilst it degenerated 
into the small weak-kneed horse found in the moors of Northern 
Germany, in some pile-dwellings, and in the “ Kreisgruben ” of 
Oldenburg. The descendants of this European horse can still be 
traced in some breeds. This view does not shut out the idea that - 
the introduction of the Asiatic horse may have contributed to the 
change of type. 
Recent—Dr. R. v. Lendenfeld has found undoubted traces of 
glaciation throughout an area of 100 sq. miles upon the highest 
part of the Australian Alps, at elevations of above 5800 feet. 
The rocks showing traces of ice-action are all granite. 
MINERALOGY AND PETROGRAPHY:.! 
Tescunite.—Dr. Carl Rohrbach? has made a thorough reéx- 
amination of all the occurrences of teschnite of which he could 
obtain specimens, and concludes that this rock is not entitled to 
the position to which it was assigned by Rosenbusch in his sys- 
tem of rock classification published in 1877. 
The paper opens with a valuable review of the literature of this 
much discussed rock-type. The best known localities are those 
in the neighborhood of Teschen, in Moravia, where the rock, as 
early as 1821, was described as a diorite. This determination 
appears to have been regarded as satisfactory until Hohenegger 
„threw doubt on it, and in 1861 proposed to call this in many 
respects peculiar group of rocks “teschnite.” This name was 
accepted by Tschermak, in 1866, for the lighter colored varieties, 
while he designated the darker ones as picrite. Zirkel, in 1868, 
and Tschermak, in 1869, first mentioned nepheline as a constitu- 
€nt of these rocks. In 1877 Rosenbusch published the results of 
his examination of these rocks, which he defined as pre-Tertiary 
Plagioclase-nepheline aggregates, and as such assigned them a 
_ very important place in his classification. Other masses of a 
similar age and mineralogical composition have been described 
by Tschermak from the Caucasus, and by McPherson in Portugal. 
Analcite, supposed to be an alteration of the nepheline, is a com- 
mon constituent at all of these localities. : 
__As the principal primary constituents Dr. Rohrbach designates 
plagioclase, augite, hornblende, biotite, olivine, magnetite an 
apatite. The augite is called “ automorphous ” when it is present 
1 Edited by Dr. Gro. H. WILLIAMS, of the Johns Hopkins Univ., ee Ma. 
? Ueber die Eruptivgesteine im Gebiet der schlesisch-mährischen K 
Tschermak’s Min. u. Petr. Mitth., vit, pp. 1-63. 
