Review of Recent Geological Literature. 221 
posit indicating that it was formed at the margin of the sea, or on laud, 
(c) The nodules of phosphate commonly rest on the surface of an un- 
derlying bed [formation?] etc. (d) The occurence in the phosphate 
layer of fossils from other and older formations, (e) The appearance of 
the phosphatic layers in company with terrestrial or littoral organisms, 
etc. 
5. On the occurrence of phosphates at the boundarij between the 
Cambrian and Lower Silurian in Neriko and West Gotland. Herr. 
J. G. Andersson in describing these deposits stated that they were 
formed in a shallow sea, and that the phosphate was obtained from 
the underlying Peltura bed by chemical corrosion of the bituminous 
limestones in this shallow sea. Herr. Hedstrom combats this view, 
referring these phosphates, as in the other case, to erosion of the beds 
<m a sea shore. This author differs also from Andersson on the condi- 
tions under which glauconite was accumlated with phosphate deposits, 
and contends that it was not formed in a shallow sea, but along shores, 
quoting occurences of this substance, noted during the voyage of the 
Challenger, etc. The facts known however hardly seem to support 
this view. The author however remarks that studies of the marine 
deposits of the littoral regions have not been made with the same thor- 
oughness as those of the deeper seas. 
6. Remarks on changes of level in Cambrian and Silurian times. 
The author claims proof of such changes of level from the corrosion of 
the Limbatus limestone in East Gotland: from the fact that the Ortho- 
caras limestones are conglomeritic in some places, the way in which 
parts [only] of thin shelled fossils of this limestone are preserved; from 
the way in which its cephalopods are heaped together, etc.: and also 
the alternating of littoral and deep water sediments. 
Various other points in relation to corrosion holes in the limestones, 
are discussed, and it is well for those interested in the study of phos- 
phatic and glauconitic deposits to read this paper in connection with J. 
Gunnar Andersson's of 1895, reviewed in this journal in February last. 
Both articles are based on practical studies of Cambrian and Ordovician 
terranes in Sweden. o. f. m. 
Tables for the Determination of Minerals bij physical properties a.s- 
certainable ivith the aid of a fevy field instruments. By Persifok 
Frazer. (4th edition, xii and 1G3 pp.: Philadelphia, J. B. Lijjpincott 
Co., 1897.) These tables are based on the system of Prof. Dr. Albin 
Weisbach, but in each edition, and especially in this. Dr. Frazer has 
made such changes and additions as the state of the science of mineral- 
ogy would warrant and such as would best adapt the tables to the use 
of Americans. As indicated by the title, the book lays no claim to an 
extended treatise on minerals, but it does claim, and that with justice, 
to furnish an aid to the ready determination of minerals by the use of a 
few simple instruments. The characteristics depended on are lustre, 
color, streak, hardness, tenacity, crystal system, habit, structure, cleav- 
age and fracture; and to these are added chemical formuhv and remarks, 
