FOSSIL PLANTS. 449 



Some authors have attempted to divide the genus Sigillaria, 

 and also the genus Lepidodendron, into a number of different 

 genera; but this attempt appears to be a failure, from the 

 great unreliability of the characters considered as specific. 

 Some of our American types might authorize such a division 

 more appropriately than any European species. Nevertheless 

 • such divisions can not be proposed in a report where all the 

 necessary materials can not be brought together and examined 

 in detail. 



Sigillaria mono-stigma, Sp. nov. PL 42, fig. 1-5. A very 

 fine and remarkable species. In its corticated state, the scars 

 (fig. 1 a and fig. 3) are broadly rhomboidal, acute at the sides, 

 marked near the obtuse upper angle by a small, round, vascular 

 scar and a central point, resembling, by its general form, that 

 of a Stigmaria, but much smaller. The surface between the 

 cicatrices is striated by straight, parallel, narrow lines, running 

 in the direction of the four axes or perpendicular to the four 

 sides of the rhomboidal scar. These scars bear on both sides, 

 from the corners of their acute angles, inwardly curved appen- 

 dages like those of some species of Lepidodendron. In the 

 decorticated state, the striae of the surface are obliterated and 

 the scars have various forms, changing from rhomboidal to 

 oval, then to arched lines or to round points only, representing 

 the vascular scars, which are generally preserved. The pas- 

 sage from one form to the other can easily be followed on the 

 figures. Fig. 4 represents a specimen apparently deprived of 

 the whole thickness of the bark. It shows the lower side of a 

 thin plate of shale, about one-eighth of an inch thick, which 

 bears upon its upper surface corresponding scars like those of 

 fig. 5. Goldenberg, in the second Liv. of his Flora Sarrcepon- 

 tana, etc., has recently published a new species — Sigillaria 

 rimosa, Gold. — which is somewhat related to our American 

 species. The general form of the scars, even of those of fig. 4, 

 is much alike ; but the essential character, viz : the position 



57 Out. 10, 1S06. 



