XV APPENDIX. 



species — that is, no one individual tree has been seen entire, and 

 showing all of the characters mentioned — but the specimens were 

 found flattened together in the same matrix, and present such 

 an uninterrupted series of gradations as to render it impossible 

 to separate them ; and to leave the impression on the mind that 

 they really belong to the different parts of the same species. 



Prof. Lesquereux has also informed me, that after figuring and 

 describing his Sligmaria niinuta, of the Pennsylvania Report, 

 from the Lower Carboniferous of the State, he found other spe- 

 cimens clearly showing very similar gradations in the surface 

 markings, and yet under circumstances rendering it positively 

 certain that they all belong to one tree. 



So far as I have been able to see, the markings on decorticated 

 surfaces all become nearly obsolete. 



In the same matrix numerous very slender grass-like leaves 

 occur that probably belong to this species. The widest of these 

 are not more than 0.13 inch in breadth, while some of them can 

 be traced to a length of more than seven inches, and yet they are 

 broken at both ends, and appear to be simple and almost of the 

 same breadth throughout the entire length. They ai'e alwa3'"s 

 flattened by pressure, and generally show no very well-defined 

 median vein, but in some cases they appear to exhibit traces of 

 about four longitudinal lines, or veins. 



Stigmaria ? (sp. undetermined). 



The specimens of this fossil in the collection are more or less 

 compressed laterally by accidental pressure, and surrounded by a 

 thin bark-like covering of shining coal. Generally they show 

 scarcely any traces of surface scars ; but one of them about 19 

 inches in length, with both ends broken away, and measui'ing at 

 the larger end (which rather suddenly enlarges), 3, by a little 

 more than 5j inches in diameter, and at the smaller 2.40 by 4.30 

 inches in diameter, retains the scars or pits on the decorticated 

 surfaces, with some degree of distinctness. These are alternately 

 arranged in obliquely ascending rows, and are simple, vertically 

 elongated depressions, deepest in the middle, and becoming 

 rapidly shallower and narrowed to nothing above and below. In 

 the direction of the spiral rows, as well as transversely, they 

 measure about 0.40 inch from the middle of one to that of the 

 next ; while the interspaces are sometimes obscurely and irregu- 

 larly a little wrinkled longitudinally. 



The whole interior, within the surrounding bark-like coating 

 of coal, is merely composed of the hard, rather fine gritty mate- 

 rial composing the surrounding matrix, and shows no traces- 

 of an eccentric pith. This latter fact and the rather elongated 

 form of the surface pits, without any ring or elevated point 

 within, render it doubtful whether or not this form can be pro- 

 perly referred to the genus Stigmaria. 



(40) 



