

1889.] BOTANICAL GAYETTE. l8$ 



tions of data have been made by isolated, individual workers, but it is 

 none the less true that these scattered facts require to be sifted through 

 a philosophical mind before they can be presented as a connected whole. 

 It is a connected view of this general character that the work before us 

 furnishes. 



This volume is taken from the magnificent Handbuch der Botanik 

 that is being prepared under the supervision of Dr. Schenk by a number 

 of noted specialists. It is really intended as an introduction to the study 

 of paleobotany, but it also contains a very considerable amount of dis- 

 criminative matter. In the short introduction he points out the value of 

 the study of plant remains, not only to geology, but principally in regard 

 to the light it throws upon the evolution of existing vegetation. The 

 characters which can be most relied upon in the identification of fossil 

 plants are next discussed. Only a comparatively few plants are so 

 so preserved as to retain their internal structure in suitable condi- 

 tion for study, and for their characterization recourse must be had 

 to marks that in living plants are usually overlooked or ignored. The 

 most important character is that furnished by nervation. The ferns, for 

 example, in which the fructification is not preserved, are arranged ac- 

 cording to certain comparatively few types of nervation, which careful 

 study has shown to be reasonably reliable. So, also, with dicotyledon 

 and monocotyledons. Most of the genera can be as clearly identified by 

 the outline and nervation of the leaves as they could be if the whole plant 

 was accessible. The arrangement of cones, scales and leaves in the coni- 

 fers furnishes a similar key to their positive determination. But, as 

 Williamson long ago pointed out, the internal structure furnishes the 



most valuable of all data. 



The methods or conditions under which plants become fossilized are 

 next described. Incrustation, petrifaction, and the more or less complete 

 change to coal are the three conditions. Then follows the main portion of 

 the work, viz.: an exposition of our present knowledge concerning the vari- 

 ous types of vegetation that have been found fossil, and the light thrown 

 by them upon existing vegetation. Beginning with the fungi, for ex- 

 ample, it is shown how the various types first appeared in time, and a 

 brief discussion is given of the more important or critical forms. The 

 algae are similarly treated, especial stress being laid on many doubtful 

 forms that are now under discussion by botanists and zoologists. From 

 these lower forms, the types of vegetation occurring in a fossil state are 

 passed in systematic review, coming ultimately to the higher forms which 

 occur in the later geologic formations and are found both fossil and living 

 at the present day.— F. H. K. 



Minor notices. 



good 



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descriptive and illustrated works published, one of the latest of which is 



