On some Anomalous Cells developed within 
the interior of the Vascular and Cellular 
Tissues of the Fossil Plants of the Coal- 
Measures. 
BY 
WILLIAM CRAWFORD WILLIAMSON, LL.D., F.R.S., 
Professor of Botany in the Owens College and in the Victoria University. 
With Plate XVIII. 
I N the eighth of my series of memoirs { On the Organisa- 
tion of the Fossil Plants of the Coal-measures 1 / I 
described the vascular axis of a Fern, Rachiopteris corrugata , 
Will., the vessels of which were filled with cells apparently 
identical with the thylosis found in some living plants. 
In Part x of the same series 2 I subsequently described 
the petiole of another Fern, Rachiopteris insignis , Will., 
the vessels of the fibro-vascular bundle of which were 
filled with cells of a similar kind. In Part ix. of the same 
series 3 I further described a number of Lycopodiaceous 
macrospores, the interiors of many of which were occupied 
by some remarkable accumulations of cells of various sizes 
and arranged in diversified ways. During the last ten years 
there have accumulated in my cabinets various other examples 
of parasitic or saprophytic cells, lodged within the tissues of 
fossil plants, revealing a condition of things existing at the 
Carboniferous epoch not undeserving the attention of 
botanists. In most of these instances what may for the sake 
of distinction be recognised as the intrusive cells are lodged 
3 Phil. Trans., vol. 167, Part i. p. 214, PL 6, Figs, 15, 16* 
2 Phil. Trans., Part ii. 1880, p. 506, PL 16, Figs. 19-20, and 21. 
3 Phil. Trans., Part ii, 1878, p. 345, Pl. 23, Figs. 65, 66, 66 a, 66 b. 
[Annals of Botany, Vol. II. Nos. Ill and IV. February 1888.] 
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