312 Miscellanea . 



I may then briefly characterize the genus and species as follows : — 



Phyllotheca. 

 Gen. Char. Stem slender, jointed, simple or branched; branches 

 springing from above the joints, not arranged in the same plane ; 

 surface smooth or longitudinally sulcated; articulations sur- 

 rounded by sheaths, the free edge of which terminates in long 

 narrow leaves, having a more or less distinct midrib. Inflores- 

 cence arranged in whorls near the extremity of certain branches. 

 I have only to add to the above characters, that the ridges of the 

 sulcated stems do not alternate at the joints in the regular manner 

 of Calamites, nor is there any trace of the peculiar tubercles so 

 generally seen in that genus (an additional proof, if such were 

 wanting, that Brongniart's original explanation of those tubercles 

 being connected with the vascular system of the sheath is not the 

 correct one, for here we have enormously developed sheaths and no 

 tubercles). The verticillate whorls of leaves, whenever I have seen 

 them perfectly expanded, seemed always elliptical as in Annularia, 

 the leaves of two opposite points of the circumference being con- 

 siderably longer than the rest. The genus is distinct from Annularia 

 by the great development of the sheath or connected base of the 

 leaves, and by the branches being inconstant, and when present, not 

 being arranged in pairs in the same plane. 



Phyllotheca australis (Br.). 

 Sp. Char. Stem simple, smooth or slightly striated ; sheaths tight, 

 shorter than the internodes, terminated by narrow leaves, double 

 the length of the sheaths, without distinct midrib. {Condensed 

 from Br.) 



Phyllotheca ramosa (M'Coy). PI. XI. figs. 2 & 3. 

 Sp. Char. Stem branched, smooth, or slightly striated ; sheaths 



half the length of the iniernodes ; leaves thin, linear, flat, twice 



to three times the length of the sheath, with a very fine indistinct 



midrib. 



This beautiful plant has the branches weeping or hanging down- 

 wards as in Casaarina, about half the diameter of the stem ; they 

 do not arise from every joint, but they do nearly ; I am uncertain 

 whether more than one spring from any one joint. Most of the 

 stems are perfectly smooth, being striated only at the articulation 

 (see PI. XI. fig. 3), while others have a delicate lineation down the 

 internodes ; the first I imagine to be stript of their bark, and the 

 latter to retain it ; and here again we have another proof of the 

 stronger affinity of our fossil to Casuarina than to Equisetum, for I 

 find by examining the living Caauarinas that the lineation of the 

 surface goes no deeper than the bark, while the elevated lines on 

 the surface of Equisetum are only the edges of strong septa going 

 towards the central hollow, and the flat spaces between those lines 

 are only the superficial coverings of tubular hollow spaces between 

 the aforesaid septa, so that destroy the surface of Casuarina and 

 you render the -stem smooth — destroy the surface of Equisetum 

 and you only increase the coarseness and strength of the sulcation. 

 I may also add (in accordance with this view) that age or size has 

 no connexion with this lineation of the surface, as is suggested by 



