i82 Mr. Thomas Hick on the 



leaves, where it preserves the same characters. Here it 

 occupies the centre of the leaf section m, but stops short 

 below the tip, a condition which is due to the fact that the 

 section is not quite median. A layer of assimilating tissue 

 lies both above and below the " melasmatic " tissue, and is 

 continued beyond it, while the whole is enclosed in an ill- 

 defined epidermis. 



3. After these descriptions there can be no hesitation in 

 recognising in Fig. 3 a longitudinal section of the same 

 kind of leaf, although there is no twig in connection with 

 it. It is taken from a photograph of a specimen in the 

 Cash Collection, prepared by Mr. Binns from material 

 collected at Halifax. Here again we have an epidermis e, 

 with the outer cell-walls cuticularised ; an assimilating 

 tissue f y beneath both the upper and the lower epidermis ; 

 two layers of "melasmatic" tissue m\ and a clear central line. 

 That this last represents the track of a vascular strand is 

 suggested by the presence of tracheal fragments at x, and 

 is made certain by other sections in which it is better 

 preserved. In some of these it is further made clear that 

 the xylem is composed of annular and spiral tracheae, while 

 the elements that represent the phloem are merely thin- 

 walled elongated cells. 



Allowing for the curvature, the length of the leaf figured 

 is over 2^ millimeters (-^ of an inch), but it is imperfect at 

 the tip and, perhaps, also at the base. 



4. Passing from longitudinal to transverse sections of 

 the leaf, one of the best and most perfect hitherto met with 

 is shown in Fig. 4, which is from a photograph of a 

 specimen prepared by Mr. James Lomax, of Radcliffe. 

 From other preparations which contain Calamitean buds 

 cut transversely, it is known that the convex side of the 

 section corresponds to the lower surface of the leaf, and the 

 more flattened side to the upper. 



By using a hand-lens in the examination of this figure 



