Review of Recent Geological Ltterature. .'X)5 
oxenic porphyrites. Kosenbusch characterizes the family Biinply Ijy 
the abundance of large ferruginous and magnesian crystals of the first 
period of consolidation. But M. Levy claims to have been able to 
identify the greater part of the rocks described by Kosenbusch under 
the name of lamprophyrea, with a rich French series comprising ker- 
santites, dioritines, basanites and fraidronites — the traps of the ohl 
authors. 
Further, in many a formation we perceive these intrusive rocks to 
correspond with flows or incontestable protrusions. It would have 
seemed logical to remove the lamprophyres from the intrusive rocks to 
class them with effusive rocks. Professor Kosenbusch prefers to 
range a part of our French rocks in his lemprophyres of intrusive 
structure, and to scatter the others through all the chapters devoted 
to Pretertiary effusives. 
In discussing Posenbusch's views of the structures of acid eruptive 
rocks, 31. Le vy notes that the former regards muscovite as in part, consol- 
idated before the feldspars, but he attributes a secondary character to 
very recent white mica. The writer holds the greater part, even of the 
primordial muscovite, to be of consolidation posterior to the (juartz. 
M. Levy's criticisms of Rosenbusch's doctrine of rock structures ex- 
tend to many particulars, but it is not necessary to illustrate farther. 
He gives convenient tables for comparison of his classification of struc- 
tures with that of Posenljusch. These are followed by an exposition 
of what is known respecting the relations which exist between the 
structure, the mode of formation [gisement) and the geologic age of 
rocks. The examination is then carried into the mineralogical compo- 
sition of rocks, and the order of consolidation of their principal ele- 
ments, considered in reference to a rational classification. Tie cites 
Rosenbusch's two principles touching order of consolidation, and main- 
tains that they are untenable as general laws. They apply sufllciently 
well to granites, syenites and a part of the gabbros. ISut they fail en- 
tirely in the gabbros of ophitic structure, in the greater part of the 
diorites and the whole of one important class of diabases. In fact, the 
experiments of MM. Fomiue and Levy demonstrate that for the great- 
er part of the rock-making minerals, the order of consolidation is the 
inverse order of fusil)ility, while some of them are real chemical pre- 
cipations taking place during the })eriod of crystallization. 
M. Levy maintains with apparent reason that the classification pro- 
posed by himself and M. Fouiiue is founded on broader principles than 
that of Kosenbusch. The fundamental principle is that of the order 
of consolidation of all the rock-elements, both those of the first and 
those of the second consolidation. The concise exposition here given 
ie prepossessing; while the princijiles of classification em]>loyed in the 
school of Kosenbusch are subjected to elective criticism, with which 
American petrographers ought at least to acquaint themselves. Com- 
parative tables of the two classifications are presented. In another 
chapter we have the results of a more particular study of the subdi- 
