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On Medullosa pusilla. 

 By D. H. Scott, LL.D v D.Sc, For.Sec.K.S. 



(Eeceived August 12, — Eead November 20, 1913.) 



[Plate 13.] 



In the second edition of my ' Studies in Fossil Botany/ I referred in the 

 following words to the fossil plant which forms the subject of this notice. 

 " A very small Medullosa (named provisionally Medullosa pusilla), the stem 

 with the leaf-bases not exceeding 2 cm. in diameter, has since been found by 

 Mr. P. Whalley, of Colne, Lancashire. The stem has three steles, and 

 agrees very closely with M. anglica, except in size."* 



In order to clear the ground for other observers, it now seems desirable 

 to give some further account of this fossil, with the necessary illustrations. 

 Though the plant differs in no important respect from the now well-known 

 species M. anglica, it is of some interest, as probably the smallest Medullosa 

 on record. 



The fossil, as Mr. Whalley informs me, comes from the Soap-stone, imme- 

 diately above the Halifax Hard Bed of the Lower Coal Measures. Its 

 horizon may thus be compared with that of the roof-nodule specimens in 

 other localities. 



I have only two sections of the stem, sent me by Mr. Whalley on 

 January 24, 1906. There are also a couple of sections received this year 

 which appear to be of the same plant, and perhaps of the same specimen, but 

 only show a leaf-base or petiole. 



Both the sections of the stem are transverse, but in one of them a stele is 

 shown partly in longitudinal section, owing, no doubt, to displacement 

 (Plate 13, fig. 2, above). This has enabled me to compare the minute 

 structure of the wood with that of M. anglica. 



General Structure. 



The extreme dimensions of the specimen as shown in the sections are 

 22 x 13 mm. ; the form is much distorted, and in the direction of the 

 longest diameter tissue has manifestly been lost. Three leaf-bases are 

 present, one of which is well preserved and practically complete, while the 

 other two are crushed and imperfect (figs. 1 and 2). They all contain 

 numerous vascular bundles, and are bounded by a " Sparganum " cortex. 



vol. lxxxvii. — B. 



* P. 441, footnote. 



R 



