Reviews — Potonie's Tree in Coal-mine. 133 



The Bibliography occupies the first 78 pages, the Catalogue of 

 Trilobites from pp. 81-148, and the Catalogue of Palasozoic non- 

 Trilobites [unfortunate word] pp. 151-177, a brief appendix of seven 

 pages being included with the author's edition. 



This Bibliograph}^ will be exceedingly valuable, and will, with 

 the Catalogues, considerably lighten the labours of those who work 

 in Pala30zoic Crustacea and Arachnida. 



It would be ungenerous to find fault with so careful a work, but 

 we may perhaps be permitted to refer to two points in the hope 

 that Mr. Vogdes will consider them in his second edition. In the 

 first place, when a species is referred to more than once, it seems 

 desirable, instead of reprinting the name itself, to substitute a 



, and at the same time to represent the name of the original 



author in a similar manner. There could then be no doubt as 

 to whether or no the same specific name had been used by two 

 authors for different forms. Take for instance Leperditia alta, 

 Conrad sp. Five authors have referred to alta, and though the 

 specialist may know there is only one L. alta, doubt cannot fail to 

 oppress the mind of the novice. It would be absolutely clear if 

 three dashes, representing respectively generic, trivial, and authors' 

 names, were used before the name of the authors referring to the 



jDarticular species, thus Vogdes, Bibl. Pal. 



Crust., etc. In the second place, it would have been better had 

 Mr. Vogdes enumerated separately the new generic and specific 

 names that he has suggested in his Catalogue, as in a work of this 

 kind they are especially liable to be overlooked. C. D. S. 



VI. — On an Erect Tree-stump with Eoots, from the Coal of 



plesberg, near osnabrijok. by h. potonie. 

 Der im Liohthop der Konigl. geologischen Landesanstalt 



UND BeRGAKADEMIE AUFGESTELLTE BaUMSTUMPF MIT WURZELN 



aus bem Carbon des Piesberges. Von Herrn H. Potonie. 

 [Jahrbuch der Konigl. preuss. geologischen Landesanstalt, 

 1889, s. 246.] 



THE " tree stump with roots " which forms the subject of the 

 present notice was found in the Piesberg Colliery near Osua- 

 briick standing in its. natural position at right angles to the plane of 

 the bedding. 



Several specimens have been found in the same locality. Of the 

 two largest specimens one is now in the Osnabriick Museum, the 

 other, described in detail by Potonie, in the Berlin Bergakademie. 



The latter specimen is displayed to advantage in the Berlin 

 Museum, as one sees from the excellent photograph in Potonie's 

 paper, and reminds one of the giant Stigmarta recently added to the 

 Owens College Museum, Manchester, In the Berlin Stigmarta 

 there is much more of the stem pi'eserved than in the Manchester 

 example ; in neither specimen can one determine to what species 

 the tree should be referred, nor indeed with any certainty fix the 

 genus, whether Lejndodendron or Sigillaria. From such surface 

 markings as are preserved on the roots Potonie names the Stigmarian 

 portion Stigmaria ficoides (Brong.), var. incequalis (Gopp.) 



