Seward. — On the genus Myeloxylon ( Brong .). 7 
Coal-measures of Oldham, in which the phloem is partially 
preserved : the drawing is hardly sufficiently detailed to 
admit of a full description, but the specimen appears to agree 
very closely with that from the Binney collection which is 
described and figured in the present paper. Kidston com- 
pares Myeloxylon to Ophioglossum vulgatum and to Osmunda, 
and speaks of it as ‘ a typical marattiaceous fern-stem ’ 1 . 
Myeloxylon from the Millstone Grit. 
It will be convenient to describe such specimens as I 
have examined under three heads : those to be considered 
first afford an addition to the short list of Millstone 
Grit plants 2 . These plant-fragments were found in a 
block of magnesian limestone, of Millstone Grit age, about 
five miles N.E. of Lancaster 3 , by Mr. J. E. Marr. The 
block is represented in Fig. 2, somewhat less than natural 
size. In the upper part of the figure a group of rod-like 
structures is shown, weathered out from the rest of the rock, 
reminding one to some extent of the structure occasionally 
seen in limestones and known as ‘ stylolites.’ Dr. Hinde, on 
seeing the specimen, pointed out the striking resemblance of 
these rods to the anchoring appendages of Hyalostelia 
Smithii (Young), one of the hexactinellid sponges 4 . 
The rods, on microscopical examination, were found to be 
isolated bundles of tissue weathered out from the rest of the 
organ of which they form a part. Among fossil plants from 
the English Coal-measures it is not uncommon to find 
specimens in which regularly defined areas in a stem or root 
have been mineralized with their minute structure perfectly 
preserved, whilst the rest of the tissue has been almost 
entirely destroyed before the infiltration of the fossilizing 
1 Kidston, loc. cit. p. 50. 
2 Etheridge, in his Catalogue of Palaeozoic fossils, mentions twenty-eight species 
of British Millstone Grit plants (Fossils of the British Islands, vol. I. Palaeozoic, 
1888). 
3 Near Caton, Geol. Surv. Map (inch scale), quarter sheet 91 N. E. 
4 For description of this sponge, see Palaeontographical Society, vol. XLI. p. 158. 
