44 On Variations of Sigillariw. 



sents the twin scars at one extremity of a row, two small 

 scars at tlie opposite end, and one from the middle of the 

 same row. 



There are various diverse and peculiar forms produced by 

 the union of the sub-cortical scars of this species. The scars 

 illustrated in Fig. 3 are upon the same specimen. Other 

 specimens show both ends acute or slenderly pointed. There 

 is also great diversity in the breadth of these scars, as they 

 vary from narrow elliptical to rotund. In some cases the 

 transverse diameter is the greater. All of these forms may 

 not, but they usually do, have a central depression, varying 

 from rotund to oblong, or even linear, and frequently appear- 

 ing only as a line or furrow, sometimes irregular or of varying 

 width, extending the whole length of the scar. Fig. 4 shows 

 three scars from one slab, illustrating these features. This, 

 and also Fig. 3, are from specimens in Mr. Jones' collection. 

 It will be readily understood how different in appearance are 

 scars having peculiar combinations of the features above men- 

 tioned. 



Another form of 8. reniformis has oblique oval or elliptical 

 scars, with ends acute and oppositely curved; length one-half 

 inch ; depression linear, width of ribs two inches. The scars 

 are very close, and the oppositely curved ends of adjacent 

 scars overlap like the cicatrices of Lepidodendron. This form 

 evidently results from the twin vascular scars not uniting 

 evenly end with end, but lapping over each other; caused 

 doubtless by oblique distortion in the growth of the base of 

 the leaf. Fig. 5 shows a portion of one row of scars. In this 

 specimen the furrows between the rows are obsolete ; and the 

 rows are not continuous, but, as it were, broken and shifted 

 laterally. The specimen is in my own collection, and is from 

 the " Diamond " seam, Scran ton, Pa. The other specimens 

 already mentioned are said by the possessor to be from the 

 " Hull" seam, Olyphant, Pa., the first above the u Diamond," 

 in that locality. 



Upon some decorticated slabs of 8. reniformis, the fluting 

 is very strong, while upon others it is entirely absent. 



Since the preparation of the above matter, I find that, in 



