OF THE FOSSIL PLANTS OF THE COAL-MEASURES.—PART XIIT. 
299 
equally anomalous combinations of internal structure, that remove it far from any 
known living form of vegetation, though it is an unquestionable Lycopod. 
We thus fail, for the present, to reach anything beyond probabilities respecting the 
true affinities of the plants described in this memoir; but, whatever may be finally 
determined as to their real systematic position, one thing is certain, viz., that in their 
internal organisation they present combinations of tissues that find no representatives 
amongst living plants. Possibly they are the generalised ancestors of both Ferns and 
Cycads, which transmitted their external contours to the former and their exogenous 
modes of growth to the latter types. In considering this possibility, we must not 
forget that in Stcmgeria we have a still living plant in which the stem of a Cycad bears 
fronds, the leaflets of which retain the dichotomous nervation of a true Fern. The 
Stangeria has retained, not only the primitive exogenous stem of some ancestral type, 
in common with its other Cycadean relatives, but also the peculiar Fern-like leaflets, 
which may also have come down to it from Palseozoic times. Hence we have here a 
combination of Fern-like features and of an exogenous mode of growth. Such being 
the case, it need not startle us if we have to conclude that a similar combination 
existed during the Carboniferous age. 
In closing this memoir, I have again to thank Mr. Spencer and Mr. Binns, of 
Halifax, for the specimens with which they have so kindly supplied me. But my 
thanks are most specially due to William Cash, Esq. Resident on the spot, his 
incessant vigilance in seeking for new material and opening out new sources of supply 
has a value to me of which I can scarcely speak too highly. 
2 Q 2 
