108 IGEN, OWL OF GIZOULOG IZ, 
phosphates and phosphatic marls are of great use to the farmer in the 
vicinity. The purely calcareous marls are discussed, and their value 
shown. The clays for pottery, brick and tile making are also briefly: 
treated, and some of them are shown to be of good quality. 
Dr. Smith’s work has been carried on unostentatiously for many: 
years. The present volume is not the first piece of good work which 
he has done. The large results which he has brought out are alto- 
gether incommensurate with the meager appropriations which have 
been at his disposal. While the co-operation of the United States Sur- 
vey has been of much service to his work, a service which he fully 
acknowledges, much credit still belongs to the state geologist himself. 
Rouiin D. SALISBURY. 
Dr. K. v. Chrustschoff, Ueber Holokrystalline Makrovariolitische 
Gesteine. Memotres de L’ Academie Imperiale des Sciences de 
Sh Letersvourng, NINE Series ome DOU Non ee Sts metens= 
bourg, 1894. 4to, 244 pp., 3 plates and 37 figures. 
The author in his introduction refers to the work already done on 
the subject, and shows how in the case of the true variolite (‘‘an 
endomorphic contact phenomenon of diabase’’) the consideration of 
the origin is simple in comparison with the genetic history of the 
orbicular structure in holocrystalline, eugranitic, plutonic rocks. The 
origin of these are entirely different. 
Finding the references to these holocrystalline orbicular rocks to 
be unavailable he collected them and presents a bibliography of the 
special studies on spheroidal building, orbicular granites, diorites, 
gabbros, and diabases. 
As the most direct means of approaching the subject Chrustschoff 
chooses six of the more noted occurrences of variolitic rocks, along 
with four new occurrences (two in Sweden, one in Silesia, and one in 
Siberia), making ten, which serve as the subject of discussion for the 
volume. With each example the author carefully analyses the varioles. 
into an inner core (kern) and various concentric rims (calotte) which 
may or may not possess radial arrangements in conjunction with their 
neighbors. The mass of the rock and each of these divisions is in turn 
studied carefully, and the optical characteristics, order of sequence in 
crystallization, and very frequently the chemical composition of the 
various constituents are discussed in detail. 
