78 On the Leaf Scars of Lepidodendron. 



statement, and many of his remarks concerning American 

 forms, fully agree with my observations of the fossils. 



It is but just to say that my investigation was undertaken, 

 and the results which are embodied in this paper were reached, 

 independently and before I found access to Prof. Schimper's 

 authoritative work, or had any knowledge of its contents. I 

 shall simply quote his remarks upon the forms which I discuss. 



In the Third Anthracite or Wyoming coal basin of Pennsyl- 

 vania, it is not only impracticable, but to any important ex- 

 tent impossible, to study coal plants in situ. The conclusions 

 herein contained have been reached by comparison of nu- 

 merous specimens from many localities in that field. In this 

 study, the partially obliterated, deformed, and anomalous 

 specimens, that are usually neglected by collectors, but which 

 are of great importance in tracing variations, have been care- 

 fully regarded. From peculiarities of form as distinct and 

 important as some features that have been used as the basis 

 of specific distinction, I could create new species. But I am 

 convinced that such forms are connecting links between others 

 already erected into species. Prof. L. Lesquereux's Memoir 

 on the coal plants of the anthracite basins of Pennsylvania, 

 contained in Sogers' report of the first Pennsylvania State 

 Geological Survey, has of necessity been largely the basis of 

 my work. 



In what I regard as the typical form of L. aculeatum, Sternb. 

 (Figs. 1, 2, PI. V; Figs. 1, 5, PI. VI), the medial line of the 

 inferior half of each general leaf scar is continued as the 

 medial line of the superior portion of another leaf scar. The 

 general scars are thus directly connected in rows, or seriate. 

 Frequently the attenuate extremities are much elongated, and 

 sometimes the scars are confluent, as shown in two places in 

 Fig. 1, PI. VI. These variations of the typical form, together 

 with somewhat similar derived forms hereafter described, fur- 

 nished the species Sag. confiuens, Sternb., L. undulatum, Sternb., 

 L. candatum, Ung., and others named by Sternberg, all of 

 which M. Schimper has already united with L. aculeatum, 

 Sternb. Each series of leaf scars is separated from its adja- 

 cent rows by an intervening furrow or band, called the mar- 



