1894.] Petrography. 947 
spinels as a consequence of the contact action. In many instances 
different combinations of inclusion and including rocks gave rise to: 
the same new products, so that it is difficult to discover the exact law 
governing the changes. In the basalts the principal inclusions con- 
sisted of single minerals, while in the more acid rocks they comprised: 
largely rock fragments—a fact probably attributable to the different. 
solvent powers of the including material. Lacroix's volume is a 
nearly complete treatise on the subject of which it treats, which is lim- 
ited, as the title indicates, to the study of inclusions in volcanic (effu- 
sive) rocks only. The author separates inclusions into two classes. 
The first comprises fragments of an entirely different nature from that 
of the enclosing rock, as granite in basalt. These he calls enalloge- 
nous (enclaves énallogénes). The second class comprehends inclusions 
more or less similar in composition to the including material. These 
he terms homogeneous inclusions (enclaves homoeogéues). Thesecond 
class embraces aggregates formed by segregation and by liquation, as 
well as true inclusions. The including rocks are also separated into 
two groups, the basaltic and the trachytic. In the first part of the 
book the enallogenous inclusions are discussed with great thoroughness. 
In the second part the homogenous inclusions are studied. In a third 
part are collected the general conclusions. Chapters are devoted to 
each class of rocks and divisions of the chapters to the character of 
the inclusions in them. Resumés and paragraphs embracing the 
results of the studies are scattered through the volume at convenient 
intervals, and a geographical index concludes the book. The number 
of discoveries made by the author in the course of his work is too 
large for discussion in this place. The book bears evidence of thorough- 
ness throughout. It is an excellent contribution to the subject of con- 
tact action. 
The Basic Rocks of the Adirondacks and of the Lake 
Champlain Region.—Kemp? gives a brief account of the coarse 
basic rocks of the Adirondacks of which the well known norite is a phase 
Associated with the norite are anorthosites, gabbros and olivine gabbros, 
all of which are more or less schistose. The anorthosites are crushed, 
and where the shattering has been most intense their plagioclase has been 
changed to a fine grained aggregate, thought to be saussurite. Augite 
and brown hornblende are present in these rocks, but not in large 
quantity. Garnets are always present. The more basic gabbros are 
dark rocks, whose plagioclase has a greenish tinge due to the abund- 
5Bull, Geol. Soc. Amer. 5, p. 218. 
