262 PROF. W. C. WILLIAMSON ON A NEW FORM 



hitherto seen the internal structure; and^ in addition,, Cala- 

 mopitus has its projecting ridges composed of longitudinal 

 wedges of vascular tissue^ separated by intervening ones of 

 prosenchyma. 



Fig. 8 shows that my strobilus exhibits the first of these 

 characteristics ; figure 7 e displays the second ; whilst^ if I 

 am correct in my interpretation^ we find the third feature 

 echoed in the longitudinal arrangement of the vascular 

 bands (fig. 7^ e e'), and in the relationship of those bands 

 to the small longitudinal canals (fig. 3, d), as well as to 

 the masses of cellular prosenchyma (fig. 7, c c') which 

 separate them. Bearing in remembrance the apparently 

 obvious fact that my strobilus is an indisputable Cala- 

 mitean fruit, and that Calamopitus is the only Calamitean 

 stem hitherto described possessing the true reticulated 

 vessels which it exhibits, it becomes more than probable 

 that some close relationship exists between the two plants. 

 If they are not actually the stem and fruit of the same 

 species, at least the fruit must have belonged to some 

 hitherto undiscovered stem with reticulated vessels closely 

 allied to Calamopitus^. It is true that, in the specimen 

 of the latter which I described, I could not trace the 

 small canal seen at the inner angle of the woody wedges 

 of other Calamites ; but I have ah^eady found specimens 

 which indicate the possibility that this apparent absence 

 may have been due to mineralization masking, by dark 

 carbonaceous deposits, what may have existed in its mini- 

 mum rather than its maximum degree. 



At first there seems to be a difficulty in admitting the 

 association of a cryptogamic fruit with an exogenous stem ; 

 but we do not escape this difiiculty by refusing to accept my 

 suggestion. No one can doubt that Calamopitus is merely 



^ Since this memoir was read I have obtained stems with reticulated 

 vessels, but otherwise like Calamodendra, to which the strobilus maj have 

 belonged. 



