LEPIDODENDREAE. 203 



shortly decurrent and loosely arranged, and have their extremities slightly 

 emarginate ; the former appears in rather shapeless casts studded with 

 irregularly shaped pad-like protuberances which are broader in the transverse 

 direction. Knorria Richteri J , also, from the hard coal of Oberhohndorf in 

 Saxony, belongs to our present group, as its author expressly states. 

 Schimper, who has also given a figure of Ancistrophyllum 2 , showed subse- 

 quently 3 that the two genera are portions of the base of the stem of Knorria 

 longifolia ; he states that he found the characters of the three genera united 

 in a stem discovered at Burbach near Thann. He refers the difference in 

 shape of the remains of the leaf-cushions to changes connected with the 

 growth of the stem, which may have affected the outer form as well as the 

 inner structure. One more genus remains to be mentioned, Dechenia, Gopp., 

 about which I refrain from expressing any decided opinion. Dechenia 

 Romeriana, Gopp. 4 , from the Lower Devonian deposits, reminds us of 

 Knorria ; D. Euphorbioides 5 from the Culm of Landshut in Silesia is a 

 rather shapeless approximately cylindrical piece of stone covered with 

 spirally disposed cushion-like projections. 



Leafy branches of Lepidodendron are excessively abundant in the 

 Coal-measures, and have essentially the habit of Lycopodiae. By the 

 disappearance of the leaves which drop off regularly, as they do not in 

 Lycopodium, the characteristic leaf-cushions are disclosed to view, and are 

 at first small, but subsequently follow the further growth of the stems and 

 branches, and increase in size. Little attention therefore is to be paid to 

 these cushions in determining the limits of the species ; and other changes 

 of form may possibly be connected with them of which we know little, owing 

 to the fragmentary character of the material, and which may therefore be 

 the source of fresh causes of error in defining species. For this reason the 

 statements of authors, that certain leafy branches must belong to certain 

 species which are known by the structure of the stem, must be accepted 

 with the greatest caution, since they scarcely ever rest on observation of 

 the actual attachment of the branches to the pieces of stem to be deter- 

 mined. The leaves themselves are of very different size and shape ; they are 

 flat, linear, and pointed, and of very considerable length in the branch figured 

 by Schimper 6 after Rohl^and identified as Brongniart's Lepidodendron 

 longifolium. Similar leaves, but much shorter and more strongly squarrose 

 and not collected into a parallel tuft, are drawn by Brongniart 7 in his Lepi- 

 dodendron elegans and L. gracile, which are both referred by Schimper to 

 the collective species L. Sternbergii, Brongn. It is true that they have 



1 Geinitz (5), p. 39; t. 4, f. 2. * Schimper (4), tt. u, 12. 3 Schimper (1), vol. ii, pp. 58 



and 118. * A. Romer (1), II, t. 14, f. i. s Goppert (1), Lief. 3-4, t. 3. 6 Schimper 



(1), t. 59, f. i. 7 Brongniart (1), vol. ii, t. 14 and t. 15, and Lindley and Mutton (1), vol. ii, 



t. 113, and vol. i, t. 4. 



