Structure of Lepidodendron and Sigillaria. 129 



XII. — On the structure of Lepidodendron and Sigillaria. 



BY HERMAN L. FAIEOHILD. 



No. 3 — On the Identity of certain Supposed Species of Sigil- 

 laria with S. lepidodendrifolia, Brongt. 



(With Plate X.) 

 Bead April 1, 1878. 



In the preceding paper of this series I attempted to show 

 that several so-called species of Lepidodendron were but natu- 

 ral or accidental variations of growth of a single species. In 

 this paper I propose to treat in a similar manner a number of 

 forms of Sigillaria. 



It is very rarely that a variation equal to that shown in Fig. 

 1, PI. X, is found upon an equal amount of surface of a single 

 fragment. And this specimen is the more remarkable, as evi- 

 dently proving the specific identity of two forms of Sigillaria, 

 widely diverse in appearance, and placed, by some writers, in 

 different sections of the genus. 



This fossil, and also the fragments represented in Figs. 2-4:, 

 were found in the " rock dump " of the Brisbin shaft, Scran- 

 ton, Pa., and were derived from a horizon not below the 

 mammoth, or E, seam of the Pennsylvania geologists. 



These fragments, and several similar ones not figured, were 

 split out of the same piece of rock with my own hands; and 

 they were so intimately associated that, taken in connection 

 with the fact that this block of roof-shale, as large as a man 

 could easily roll, contained no other plant remains, it is almost 

 certain that they are portions of one individual. 



The specimen shown in Fig. 5 was presented to me by Mr. 

 C. Farnham. of Scranton. Its locality was somewhere in the 

 Lackawanna basin. 



Fig. 6 represents a portion of a large slab of S. lepidoden- 

 drifolia Brongt., from the Hampton mine, Scranton ; and, on 

 the reliable authority of the superintendent, Mr. B. C. Green, 



