On the Leaf Scars of Lepidodendron. 89 



PI. VI, might be fairly called crenatum. So might L. obtusum, 

 Lesq., as far as the vascular scars are concerned. This com- 

 parison could be greatly extended, and might result in closely 

 interweaving many species. What was said in the beginning 

 of this paper, regarding the blending of the species and the 

 difficulty of separation, is pertinent just here. The certain de 

 termination of the species will require a thorough study of all 

 the organs. If the fifty -nine species which Prof. Schimper 

 preserves should ultimately be reduced one-half or more, it 

 will not be an unexpected result. And that L. aculeatum 

 should have been thus multiplied by even so eminent a 

 palaeontologist as Prof. Lesquereux, at a time when collections 

 of coal plants were few, and opportunity for collection and 

 study limited, is not in the least surprising. The number 

 could very easily have been increased. 



For the purpose of ready comparison, I have placed in tabu- 

 lar form the descriptions of the several species which I am 

 confident are identical. If they are not identical, then consist- 

 ently there is no alternative but to establish from the inter- 

 mediate forms a great and indefinite number of new species. 

 The description of aculeatum is Prof. Schimper'sj the others 

 are the originals. 



To prevent possible misconception, I would mention that the 

 figure of L. aculeatum in Dana's " Manual of Geology," p. 324, is 

 extremely incorrect. It seems to have been taken from Fig. 

 8, Tab. VI, of Brown's " Lethsea Geognostica," and there called 

 L. obovatum, Sternb. If the figure accurately represents the 

 fossil, the latter is either very strangely distorted or an en- 

 tirely distinct species. To find such a figure of L. aculeatum 

 in the lately revised edition of this standard work, is an em- 

 phatic illustration of the uncertainty which still attends the 

 specific characters of this genus. 



The appended list of the figures gives the localities of the 

 fossils as precisely as possible, and also the places where they 

 are deposited. Besides the collections there named, the splen- 

 did cabinet of the Wyoming Historical and Geological Society 

 contains material confirming ray statements. It was im- 

 practicable to figure with this paper the large specimens which 

 show conclusively the nature of the forms herein discussed. 



