54 The American Geologist. July - 1903 - 
work involved in relegating- a rock to its proper place in the 
system may at first seem appalling. Nevertheless, it must be 
remembered that, but a few years ago, the feeling prevailed 
that the modern method of petrographic study could never 
come into general use, owing to the difficulty and expense of 
preparing thin sections. 
Tables and illustrations of the methods of calculation are 
provided which, however formidable they appear, unquestion- 
ably afford a way out of the existing confusion and indefinite- 
ness. The petrologist who adopts the system is enabled to state 
his results definitely and with precision. It is possible, even nec- 
essary, for him to show by his nomenclature how thorough and 
exhaustive has been his work. The system is unquestionably 
a possible one, and one capable of indefinite refinement and 
expansion, as the needs of the science demand. As to its gen- 
eral acceptance, time alone can tell. 
It may be well to add in this connection that Dr. Washing- 
ton has prepared, with especial reference "to the new system, 
a compilation of all rock analyses made since the time of the 
last edition of Roth's Beitrage zur Petrographie, etc. (1884). 
This work, it is understood, is nearly ready for publication. 
g. p. M. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
On Batrachian and other footprints from the Coal Measures of Jog- 
gens, X. S. By G. F. Matthew, LL.D., etc. [Bull. Nat. Hist. Soc. 
» of New Brunswick, Vol. V. Xo. 21, 1903.] 
Some small footprints from the Coal Measures of Joggins. Nova 
Scotia, which proved so fruitful a locality for the remains of small 
Microsaurians under the search of the late Sir W. J. Dawson, show that 
the interest of this locality is not exhausted. 
The Batrachian tracks are three in number, and the species are re- 
ferred to the genera Thenaropus, King, and Baropus and Dromopus of 
Marsh. One of the tracks is supposed to belong to King's genus 
above mentioned but to be prints of the forefoot only. The other two 
are in consecutive series and show well the mode in which these ani- 
mals progressed. One had a somewhat heavy tread and some of the 
