368 KIDSTON : THE FLORA OF THE CARBONIFEROUS PERIOD. 
L. and H. is founded on such a condition of Trigonocarpus, and is 
quite distinct from the genus Carpolithes as defined above. 
Plate LXV., figs. 3a., 36, 3c, show three specimens of Trigonocarpus 
removed from their pericarp, with the three prominent ridges. 
CONIFERiE. 
From what has been stated when describing the Cordaiteoe it is 
seen that true members of the Coniferce are very rare in British 
Carboniferous rocks. The only example which has come under 
my notice is a small specimen of Walchia imbricata Schimper (Plate 
LXIIL, fig. 1), which may possibly be only a form of Walchia pini- 
formis Sternberg, from the Upper Coal Measures passed through 
when sinking the shaft of the Hamstead Colliery, Great Barr, near 
Birmingham. 
In Walchia Sternberg are placed trees of a very Araucarian-like 
habit and growth. The branches are regularly pinnate, being 
arranged in two opposite or alternate rows. The spirally-placed 
leaves are more or less sickle-shaped, coriaceous, keeled, and widen 
towards their decurrent base. The fructification consists of small 
terminal cones, whose detailed structure has not yet been clearly 
made out. There is reason to believe, however, that Walchia holds 
a close affinity with the recent Araucaria. 
GlNKGOACE^. 
The type and only existing species of the Ginkgoacece is the 
Maidenhair Tree of Japan and China — Ginkgo biloba L. = {Salisburia 
adiantifolia Smith). That Ginkgo is a very ancient plant type and 
extends far back in geological times has been clearly shown, but it is 
doubtful if the Nceggerathia flabellata L. and H. from the Lower 
Coal Measures, Bensham Seam, Jarrow Colliery, which Saporta 
includes in his genus Ginkgophyllum under the name of Ginkgo- 
phyllum flabellatum, holds any real affinity with the true Ginkgoacece. 
The leaves of Ginkgo are broadly cuneate, with a long slender petiole. 
The apex is irregular, and frequently divided into two or more cuneate 
lobes. The nervation spreads fan-like from the base of the leaf. 
The Ginkgoacece are separated from the Coniferce on account of their 
mode of fertilisation, which takes place through the agency of anthe- 
rozoids. 
