8 Hick, on Rachiopteris cylindrical, Will. 



majority of the transverse sections I have seen, the 

 central elements include one or more groups of small 

 ones, which resemble in appearance the protoxylems of 

 recent vascular bundles. When two such groups are 

 met with, the appearance is as if a single group had, in 

 some way, been divided. When three, four, or five 

 groups are met with, as is often the case, they are 

 arranged symmetrically round the centre, and look as 

 though they had originated by division from a smaller 

 number. 



As to the nature of the elements of the xylem, the 

 sections at my disposal do not enable me to speak 

 altogether without reservation. The larger are probably 

 tracheides, as good longitudinal sections, No. 127 for 

 instance, show. In this section the wall markings are 

 scalariform, the pits stretching for the most part from one 

 angle to another. But in some slightly oblique transverse 

 sections, represented by No. 114, the pits appear to be 

 much less elongated and approach an elliptical form. 



The case of the^ smaller elements is not quite so 

 certain. In the longitudinal section just referred to, they 

 present themselves as scalariform structures quite similar 

 to the larger ones, save for the smaller diameter. The 

 same may be said of the oblique transverse sections, 

 where the markings of the large and small elements 

 appear to be the same. In No. 127, however, there are 

 suggestions at one or two points of a spiral marking, but 

 whether these are actually spiral, or are really scalariform 

 markings altered in some way, it is impossible to say. 



The position then as regards the xylem is this. In 

 tranverse sections we have one or more groups of small 

 elements that may be interpreted as groups of protoxylem, 

 but this interpretation has not so far been confirmed by 

 satisfactory evidence that they have spiral or annular 

 markings. 



