terminate abruptly; each rootlet which they send forth was jointed to the little ring or dimpled knob at the bottom of the stigmata; and the appearance of the whole, as it radiated from the central mass, whence the carved trunk proceeded, somewhat resembled that of an enormous coach-wheel divested of the rim. Unfortunately we cannot yet complete our description of this strange plant. A specimen, traced for about forty feet across a shale bed, was found to bifurcate atop into two great branches,--a characteristic in which, with several others, it differed from most of the tree-ferns,--a class of plants to which Adolphe Brogniart is inclined to deem it related; but no specimen has yet shown the nature of its foliage. I am, however, not a little disposed to believe with Brogniart that it may have borne as leaves some of the supposed ferns of the Coal Measures; nowhere, at least, have I found these lie so thickly, layer above layer, as around the stems of Sigillaria; and the fact that, even in our own times, plants widely differing from the tree-ferns,--such, for instance, as one of the Cycadeæ,--should bear leaves scarce distinguishable from fern fronds, may well reconcile us to an apparent anomaly in the case of an ancient plant such as Sigillaria, whose entire constitution, so far as it has been ascertained, appears to have been anomalous. The sculpturesque character of this richly fretted genus was shared by not a few of its contemporaries. The Ulodendra, with their rectilinear rows of circular scars, and their stems covered with leaf-like carvings, rivalled in effect the ornately relieved torus of a Corinthian column: Favularia, Knorria, Halonia, many of the Calamites, and all the Lepidodendra, exhibited the most delicate sculpturing. In walking among the ruins of this ancient flora, the Palæontologist almost feels as if he had got among the broken fragments of Italian palaces, erected long ages ago, when the architecture of Rome was most ornate, and every moulding was roughened with ornament; and in attempting to call up in fancy the old Carboniferous forests, he has to dwell on this peculiar feature as one of the most prominent, and to see, in the multitude of trunks darkened above by clouds of foliage, that rise upon him in the prospect, the slim columns of an elder Alhambra, roughened with arabesque tracery and exquisite filagree work. [Illustration: Fig. 29. SIGILLARIA RENIFORMIS. (Nat. size.)] [Illustration: Fig. 30. SIGILLARIA PACHYDERMA. (One fourth nat. size.)] [Illustration: Fig. 31. STIGMARIA FICOIDES. (One fourth nat. size.)] [Illustration: Fig. 32. FAVULARIA TESSELLATA. (One fifth nat. size.)] [Illustration: Fig. 33. LEPIDODENDRON OBOVATUM. (Nat. size.)] [Illustration: Fig. 34. CYCAS REVOLUTA. (_Recent._)] [Illustration: Fig.35. ZAMIA PUNGENS. (_Recent._)] [Illustration: Fig. 36. ZAMIA FENEONIS (PORTLAND OOLITE.)] [Illustration: Fig. 37. MANTELLIA NIDIFORMIS. (Portland Dirt-bed.)]