XVIl] STIGMARIA 247 



ing the vascular bundle. A few obliquely cut tracheae are 

 seen in this section traversing the connecting band of paren- 

 chyma t, fig. 210, A. 



A point of biological interest in connexion with Stigmaria 

 rootlets is the occasional presence of hypertrophied cells, the 

 large size of which is due to the attacks of a fungus named by 

 Weiss ^ Urophlyctites stigmariae. 



In addition to Stigmaria ficoides, which is by far the 

 commonest form, a few other species have been founded on 

 external characters. One of these is represented by Stigmaria 

 stellata, Goepp.^ characterised by the presence of radially dis- 

 posed ridges and small tubercles surrounding each rootlet-scar. 

 Kidston refers to Goeppert's species as a Lower Carboniferous 

 type. We have no evidence as to the meaning of the stellate 

 ridges and tubercles, nor have we any reason to suppose that 

 this form differed essentially in structure from Stigmaria 

 ficoides. 



1 Weiss, F. E. (04). 



2 Goeppert (41) PL x. Lief. i. ii. ; Williamson (87) A. PI. xiii. fig. 78 ; Eich- 

 wald (60) PL XV. ; Kidston (94) p. 254. 



