LEP1DODENDREAE. 2OI 



the group which we are considering, till Goppert, who had at first taken up 

 the same position \ came forward in support of the view that it belongs as 

 a cast-form to species of Lepidodendron 2 . He cites Lepidodendron Velt- 

 heimianum and Knorria imbricata as forms which belong to one another, 

 and tries to prove this by figuring numerous specimens. His ideas have 

 met with much assent, but they have not been able to triumph over all 

 doubts. Schimper 3 both before and since has taken the opposite view, 

 and so has Heer 4 ; and Weiss 6 has recently spoken doubtfully and cautiously 

 on this point, resting chiefly on the fact that the Knorriae which are scat- 

 tered through the Devonian system and are abundant in the Culm are 

 scarcely, if ever, found in the higher members of the Carboniferous formation 

 which are full of Lepidodendrae, but are replaced by Aspidiariae and Ber- 

 geriae. He concludes from this 6 , ' that at all events it is not every Lepido- 

 dendron that has a Knorria for a cast.' Many figures of Knorriae are to be 

 found in the works quoted, in Schmalhausen 7 and in Schimper 8 . In the 

 typical state the entire surface of the stem is occupied by spirally disposed 

 protuberances running a greater or less distance down the stem, and ending 

 above in a conical point pressed close to the stem but separated from it by 

 a sharp furrow ; at the extremity of this point when the preservation is very 

 good is a depression, deeper or shallower as the case may be, which is con- 

 sidered by all authors, and not without reason, to contain the scar-trace 

 of the foliar bundle. The length and shape of these leaf-cushions, their 

 acute or more obtuse terminations, their looser or more crowded arrange- 

 ment, their greater or less convexity were then used to distinguish a large 

 number of species in the genus, but these have been all finally united again 

 by Goppert 9 in one category as states of preservation of a few Lepido- 

 dendrae, Lepidodendron Veltheimianum, and L. aculeatum. In this pro- 

 ceeding he relies especially on two fragments from the quarries of Landshut 

 in Silesia, the different faces of which he has figured from photographs 10 . 

 One of these specimens n certainly shows quite different leaf-scars on various 

 parts of its circumference, some- of which represent a typical Knorria, the 

 others a Bergeria, though in a rather rough state of preservation. As the 

 narrow fissure between the conical terminations of the leaf-cushions in 

 Knorria and the surface of the stem is filled with a rind of coal, certain 

 portions of tissue have bfcen preserved in this case on the upper side of the 

 cushion when the cast was made, which had disappeared by that time in 

 the places where we see scars of Bergeria. Another specimen, that of 

 Knorria princeps figured by Goppert 12 5 which I have had opportunity of 



1 Goppert (1) and (12), p. 195. 2 Goppert (19), p. 512. 3 Schimper (4). * Heer 



(5), vol. 2 I, p. 421. 3 Weiss (3). 6 Weiss (3), p. 161. 7 Schmalhausen (3), tt. 3, 4. 



8 Schimper (1), t. 65. 9 Goppert (19). 1C Goppert (19), tt. 39-41. u Goppert (19), 



t. 39, ff. 3 A, 4 D ; t. 40, f. i u. 12 Goppert (12), t. 31, f. i. 



