1870.] DAWSON-—STRUCTURE OF SIGILLARIA ETC. 489 
bark of elongated or prosenchymatous cells. The author stated 
that Prof. Williamson had enabled him to examine stems found in 
the Lancashire Coal-field, of the type of Binney’s Sigillaria vascu- 
laris, which differed in some important points of structure from his 
specimens; and that another specimen, externally marked like 
Sigillaria, had been shown by Mr. Carruthers to be more akin to 
Lepidodendron in structure. ‘These specimens, as well as the Sigil- 
laria elegans illustrated by Brongniart, probably represented other 
types of Sigillarioid trees ; and it is not improbable that the genus Sr- 
gillaria, as usually understood, really includes several distinct generic 
forms. The author had recognized six generic forms in a previous 
paper and in his ‘ Acadian Geology;’ but the type described in 
the present paper was that which appeared to predominate in the 
fossil Sigillarian forests of Nova Scotia, and also in the mineral char- 
coal of the coal-beds. This was illustrated by descriptions of 
structures occurring in erect and prostrate Sigillaric, on the surface 
of Sternbergia-casts, and in the coal itself. 
The erect Calamites of the coal formation of Nova Scotia illus- 
trate in a remarkable manner the exterior surface of the stems of 
these plants, their foliage, their rhizomata, their roots, and their 
habit of growth. Their affinities were evidently with Equisetacez 
as Brongniart and others had maintained, and as Carruthers and 
Schimper had recently illustrated. The internal structure of these 
plants, as shown by some specimens collected by Mr. Butterworth, of 
Manchester, and soon to be published by Prof. Williamson, showed 
that the stems were more advanced in structure than those of mo- 
dern Hyuiseta, and enabled the author to explain the various ap- 
pearances presented by these plants, when the external surface is 
preserved, wholly or in part, and when a cast of the internal cavity 
alone remains. It was further shown that the leaves of the ordinary 
Calamites are linear, angular, and transversely wrinkled, and dif- 
ferent from those of Asterophyllites properly so called, though some 
species, as A. comosus, Lindley, are leaves of Calamites. 
The Calamodendra, as described by Cotta, Binney, and others, 
and further illustrated by specimens from Nova Scotia, and by 
several interesting and undescribed forms in the collection of Prof. 
Willamson, are similar in general plan of structure to the Cala- 
mites, but much more woody plants; and, if allied to Equisetacee, 
are greatly more advanced in the structure of the stem than the mo- 
dern representatives of that order. Specimens in the collection of 
Prof. Williamson show forms intermediate between Calamites and 
Calamodendron, so that possibly both may be included in one family ; 
but much further information on this subject is required. The 
tissues of the higher Calamodendra are similar to those of Gymno- 
spermous plants. The wood or vascular matter of the thin-walled 
Calamites consists of multiporous cells or vessels, in such species as 
have been examined. 
In conclusion, a Table was exhibited showing the affinities of 
Sigillarie, on the one hand (through Clathraria and Syringodendron) 
with Lycopodiaces, and on the other hand (through Calamodendron) 
VOL, XXVI,—PART I. 2N 
