APPENDIX. XIV 



placed in the usual obliquelj^ ascending rows so as to present a 

 quincuncial arrangement, smooth below, Interspaces smooth, 

 somewhat less thftn the breadth of the cicatrices, measuring 

 transversely, and half their breadth measuring in the direction 

 of the oblique rows. Leaf scars small, placed at the upper end 

 (and usually a little excentric to the right) of the cicatrices, sub- 

 rhombic, about as wide as long, with upper side convex in out- 

 line, the lateral angles rounded, and the base abruptly pointed ; 

 sometimes with the entire outline subcircular, smooth, or without 

 any visible vascular pits within. 



The above description is taken from a portion of a flattened 

 branch about an inch and a half wide, showing the cicatrices quite 

 distinctly. But these markings present a great diversity of ap- 

 pearances on different portions of the different sized branches and 

 trunks; and, consequently, the description would not apply to all 

 of its parts. In some of the impressions of still smaller branches, 

 or individuals, the cicatrices are more crowded laterally, more 

 elongated, proportionally narrower, and, as seen in a cross light, 

 present a decided elongate-rhombic outline, the interspaces being 

 proportionally narrow, so as to make the cicatrices appear as if 

 acutely pointed, both above and below. In this aspect, the leaf 

 scars are scarcely seen, and the whole surface presents much the 

 appearance of the figure of SigillaiHa Ghemungensis, given on 

 page 275 of the Report on the fourth Geological District of New 

 York. Even in these specimens, however, when viewed in a 

 different light, the cicatrices can be seen to be really more or less 

 rounded above, and the leaf scars obscurely defined. On still 

 larger branches, the cicatrices become more and more faintly 

 defined, and the leaf scars proportionally more distinct and more 

 scattering, so that the surface looks very much like that ^of a 

 Stigmaria. In following the markings to larger and larger 

 branches, or individuals, the cicatrices are seen gradually to be- 

 come obsolete, and longitudinal ridges begin to be developed. On 

 fragments, apparently of the trunk of the same tree, these ridges 

 a,re found to be from 0.25 to 0.46 inch in breadth, nearly flat (with 

 sometimes very obscure traces of irregular longitudinal stria3), 

 and separated by narrow irregularly interrupted furrows; while 

 a single row of the small scars occurs along the middle of each, 

 separated by intervals of about 0.50 inch. Again other speci- 

 mens, apparently of portions of the trunk, show the ridges to 

 have become obsolete or nearly so ; but the leaf scars are still 

 seen, more widely separated, and more obscurely defined. These 

 longitudinally ridged specimens, therefore, present very nearly 

 the characters of Sigillaria. Hence, it becomes a matter of 

 some doubt to which one of the three genera, Lepidodendron, 

 Stigmaria, or Sigillaria, the species should be referred. 



It is true that the specimens seen are not in such a condition 

 as positively to demonstrate that they all belong to the same 



(39) 



