Palaeontologie. 541 



Carboniferous strata with which they are unconformable. He 

 nevertheless recognizes the plant remains as having a notable 

 resemblance to the flora of the Carboniferous and Millstone 

 Grit, and in endeavoring to account for this interesting fact, 

 quotes the late Sir William Dawson who, vvhile recognizing 

 the similarity, accounted for it on the ground of „specific 

 difference" and referred the plants to the Middle Devonian. He 

 further suggests two hypotheses to account for the similarity 

 of floras so widely separated in time. One Suggestion is that 

 „the Carboniferous plants best known to us, are to a great 

 extent the species which flourished in marshy lands. Only in 

 such places would deposits of coal of that time be formed, and 

 these are the deposits which have been most extensively 

 exploited. As already shown, the Little River Plant beds 

 accumulated under similar conditions, and so present us with 

 species of plants, insects and crustaceans parallel to their later 

 congeners of Carboniferous time." The second hypothesis is 

 that „the removal and reappearance in a changed form, of the 

 marsh-land flora of the Little River Group, may have been 

 influenced by variations in annual temperature." A change of 

 ten degrees (F.) in the mean annual temperature of a region, 

 would have a profound influence on the Vegetation. Greater 

 changes than this are registered in the successive epochs of 

 geological time in the same region. „Reference is made to the 

 insect remains which, so far as described by Dr. Scudder, 

 appear to be Carboniferous, though the author also states that he 

 found species differing from the Carboniferous. He concludes 

 that „nothing has been done to invalidate the strong evidence 

 from stratigraphy and regional metamorphosis, which separates 

 these beds from the Carboniferous System." d. P. Penhallow. 



POTONIE, H., DieSilur- und dieCulm-Flora des Harzes 

 und des Magdeburgischen. (Mit Ausblicken auf die 

 anderen alt-paläozischen Pflanzenfundstellen des Variscischen 

 Gebirgs-Systems. (Abhandlungen der Königl. Preussischen 

 Geologischen Landesanstalt. Neue Folge. Heft 36. Berlin 

 1901. [Ausgegeben 1902.] 183 pp. Mit 108 Figuren.) 



Behandelt die Silurflora des Dill- und Lahn - Gebietes, 

 des Kellerwaldes, des Harzes und von Gommern bei Magde- 

 burg, die Devonflora des Kellerwaldes und des Harzes, über 

 die mangels an Resten kaum etwas zu sagen ist, und die Culm- 

 flora des Harzes und des Magdeburgischen. Nach der jetzigen 

 Auffassung der im Kellerwalde und im Harz kartirenden Geo- 

 logen gehören gewisse Quarzite, Plattenschiefer, Grauwacken der 

 erstgenannten Gebieten zum Silur und die Pflanzenreste in 

 diesen Gesteinen haben daher ein besonderes Interesse, und 

 zwar um so mehr, als es sich um die ältesten bekannten Land- 

 pflanzen-Reste handelt. Unter diesen finden sich sehr schöne 

 Farn-Wedel -Theile und Lepidophyten- (Lycopodiales) Reste, 



