2 Hick, on Rachiopteris cylindrical, Will. 



have mainly relied are a number of sections prepared 

 by Mr. James Binns, of Halifax, and now in the Cash 

 Collection at the Manchester Museum, Owens College, 

 but these have been supplemented by others. 



Anatomy and Histology. 



Transverse sections of Rachiopteris cylindrica have a 

 circular or elliptical outline. The diameter of the circular 

 ones varies slightly from an average of 2 mm. (J^in.), 

 while the elliptical ones are somewhat larger, and 

 measure for the most part 2'imm. {fain.) by 1*9 mm. 

 (xgin.). It is obvious, therefore, that the objects to be 

 dealt with are small, but there is nothing to show that 

 they are in an immature state. In most of them one 

 recognises without difficulty (Fig. 1) a central cylinder 

 or stele, surrounded by a cortex, and a peripheral or 

 epidermal layer. The stele, when single, is circular in 

 transverse section, with a diameter varying between 0*4 

 and 0*75 mm. (fa and xfein.). In many cases, however, 

 it is preparing for, or in a state of, division, and is then 

 more or less elliptical, measuring 1 by o*8 mm. (fa by 

 ^oin.). The cortex, including the epidermis, varies in 

 thickness from 0*4 to o*8 mm. (fa to fa in.). 



The Epidermis. 



The peripheral layer or epidermis is not usually quite 

 distinct, but when it is, as in No. 115,* it presents itself as 

 a single layer of cells. No signs of stomata have yet been 

 seen in it. In some sections, such as the one just referred 

 to, it is provided with a covering of multicellular hairs, 

 the density of which varies in different specimens, while 

 in some no hairs are visible. In these last, however, it is 



* Here and throughout the figures refer to the Register of the " Cash " 

 Collection of sections of Carboniferous Plants in the Manchester Museum, 

 Owens College 



