Geology and Mineralogy . 401 



is similarly separated into the Comanchean, of equal rank with 

 the Jurassic and Cretaceous. The discussions are based upon the 

 doctrines of the permanency of continents and that of the world- 

 wide character and periodicity of the great deformative move- 

 ments, the latter being used as the basis for the separation of the 

 Mississippian and Comanchean. The problems of the Permian 

 and Pleistocene receive considerable attention, the former occu- 

 pying 59 pages, much in small print, and the latter 190 pages. 



"As stated in the preface "the familiar calling of the biological 

 roll under each period is abandoned, and will perhaps be missed." 

 The paleontological side of the earth history is subordinated in 

 space to the paleogeographical and the problems dealt with are 

 chiefly the origins and mutations of the faunas and floras. 



From the preceding necessarily brief statements it is seen that 

 these volumes are strikingly radical and stimulating both in their 

 method of treatment and in the subject matter. For these rea- 

 sons, however, they do not supplant the standard manuals at 

 present before the public, but rather supplement them. Taken 

 in connection with Dana's Manual and the fourth edition of 

 Geikie's Text Book, the advanced student is, at present, admira- 

 bly provided with condensations of geological knowledge. The 

 authors state that the "three volumes are designed to furnish the 

 basis for a year's work in the last part of the college course, or in 

 the earl} r part of a graduate course." Many teachers, however, 

 may question whether such students are sufficiently mature to 

 use these volumes as texts, but they certainly furnish much lecture 

 material for the teacher and form excellent reference books for 

 mature students. To the young student, with an insufficient 

 basis of facts and limited experience in their interpretation, 

 the prominence given to hypothesis, though otherwise an excel- 

 lent feature, may be dangerous, possibly leading him to neglect 

 the detail of the science for this more attractive field. Geology 

 is a science which has suffered much in the past from ungrounded 

 speculation, since speculation is easier than investigation, and 

 interpretations must be largely based upon the unseen. These 

 volumes, however, should be carelully read by every advanced 

 student in geology and no teacher can consider himself abreast 

 of the times until he has become familiar with them. They will 

 also be found intelligible and interesting by men in other branches 

 of science. j. b. 



2. Traite de Geologie; par A. de Lapparent. 5th edition 

 in three volumes, 2015 pages. Paris, 1906 (Masson & Co.). — 

 This elaborate work of the eminent French geologist and 

 geographer, considerably enlarged from the previous edition, 

 suggests a comparison with the three-volume Geology of Cham- 

 berlin and Salisbury, lately completed. De Lapparent devotes 

 one volume to "phenomenes actuels," morphology, physiography, 

 erosion, volcanoes, earthquakes and so on, and two volumes to 

 " geologie proprement dite," under which an elaborate review of 

 historical geology is presented, covering all parts of the earth, 



