TEMPSKYA. 157 



If we turn to the histological structure of Tempskya we find, as 

 a rule, the mineralization of the tissues has been very partial, as 

 indeed the extremely porous texture of most of the specimens 

 sufficiently indicates. Schenk's figure affords a good example of 

 this incomplete preservation. In some specimens in the Botanical 

 Department of the British Museum, to which Mr. Carruthers was 

 kind enough to draw my attention, the structure is unusually well 

 shown. Unfortunately in the case of some of these slides there 

 seems to be some doubt as to the exact locality from which the 

 specimens were obtained. I am also indebted to Mr. Boodle of 

 the Royal College of Science for the opportunity of examining 

 some very interesting sections of Tempskya in his possession, of 

 which he hopes shortly to publish a full description. 



The chief feature in specimens of Tempskya in which the details 

 are more perfectly preserved is the large number of root sections 

 of various sizes ; the central vascular bundle is occasionally 

 exceedingly distinct, and shows a diarc xylem group, of which 

 the larger tracheids have a scalariform or reticulate pitting. 

 Immediately surrounding the tracheids there is a space left by 

 the disorganization of the phloem ; and, external to this, several 

 layers of thick-walled elements, followed at the periphery of the 

 root by a thin band of parenchyma which, in some cases, shows 

 a remarkably distinct piliferous layer with long and narrow root 

 hairs. These sections in which the root hairs have been preserved 

 appear to be identical with those figured by Corda in Protopteris 

 Cottai. 1 Transverse sections of the roots of Dicksonia antarctica 

 agree very closely with these fossil roots ; we have the same type 

 again in Protopteris microrhiza and P. confluens, Stenz., as figured 

 by Stenzel. 2 



In addition to these smaller diarc root bundles, some of the 

 British Museum slides of Tempskya show larger groups of tracheids 

 of a more or less triangular form which may be sections of larger 

 root axes. There is distinct evidence in the great variation in size 

 of the root sections that we are dealing with a mass of branched 

 root structures. 



Associated here and there with these adventitious roots, some 

 of the examples of Tempskya occasionally show sections of larger 



1 Flor. Vorwelt, pi. L, figs. 1-5. 



Acta Ac. Ctcs. Leop.-Car. vol. xxvi. 1858, pis. xviii. and xix. 



