OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
471 
Salisburia, whether in its young state, when the inner bark consists, as represented in 
fig. 28, of undifferentiated primitive parenchyma, or, in a later stage of growth, when 
the bark is distinctly differentiated into an inner translucent phloem and an external 
phellem layer. These correspondences between the carboniferous Dadoxylon and the 
living Salisburia suggests another query. The resemblances between the fossil 
Trigonocarpums of the Coal-measures and the fruits of the Gingko have long been 
noticed. Do not the facts just mentioned increase the probability that these Trigono¬ 
carpums are the fruits of Dadoxylon? I not only think they do, but these facts 
suggest the further possibility, not to say probability, that our Dacloxylons may be 
the remote Carboniferous ancestors of the oolitic Baierias —already recognized as the 
ancestral forms whence sprang the Salisburias of Cretaceous and yet more modern 
times. 
I have again to recognize my obligations to Messrs. Cash, Spencer, and Binns, of 
Halifax; to Mr. Hick, of Harrogate; to Mr. Wild, of Ashton-under-Lyne; and to 
Messrs. Butterworth and Earnshaw, of Oldham, for their valuable aid in searching 
for specimens calculated to aid my investigations. 
Index to the Plates. 
PLATE 27. 
Astromyelon Williamsonis. 
Fig. 1. Transverse section of a non-exogenous branch (?). Enlarged 70 diameters. 
a. Vasculo-cellular axis, b and c. Inner cortical zones, d. Radiating 
cellular laminae, e. Outer cortical parenchyma. Mr, Spencer. 
PLATE 28. 
Transverse section of a stem. Enlarged 55 diameters, a. Large cellular 
medulla, b. Young exogenous zone, feebly developed, c. Innermost bark. 
d. Radiating laminae, d". Lacunae separating the laminae cl. e. Peripheral 
parenchyma. Messrs. Cash and Hick. 
PLATE 27. 
Fig. 3. Transverse section of a stem. a. Medulla, a'. Cluster of thick-walled 
vessels at the inner angle of each large vascular wedge. b. Vascular 
wedges, c. Innermost bark. d. Radiating laminae, e. Outer parenchyma. 
Mr. Spencer. 
Fig. 2. 
3 p 2 
