II A R D IV I CKE ' S S CIE NCE-GOSSIP. 



\2' 



"dichotomy,"' which is so well illustrated in the 

 branching of lepidodendron. The stem of lepi- 

 dodendron after attaining a certain height divided 

 almost exactly into two branches ; these branches 

 after growing awhile divided in a similar manner, 

 and this bifurcating went on until a crown of branches 

 was formed. 



The sigillaria, however, appear, so far as my 



side by side with sigillaria, the former may fre- 

 quently be met with in a branching condition, but 

 the latter, never. If dichotomy ever did take place 

 in sigillaria, some examples of it must have been 

 met with in our coal-fields, and it is quite possible 

 that other observers may have met with such. If so, 

 they would confer a boon upon students of this 

 subject by making the facts known. Every little 



Fig. 79. — Sigillari.i (rcbtored) ; b, leaflet ; c and d, impressions of leaves left 

 on bark ; e, section of stem ; f, portion of cylinder. 



experiences go, to have very rarely branched — so 

 rarely, indeed, that I have never succeeded in finding 

 a single case of dichotomy in any real sigillaria from 

 our Yorkshire carboniferous formation, although I 

 have been on the look out for it for many years, 

 and have examined hundreds of specimens of sigil- 

 laria ill situ, and in private and public museums. 

 In our coal balls, where lepidodendron lies often 



fact in connection with this singular plant is worthy 

 of being recorded, for notwithstanding the fact— of 

 which we have abundant proof— that sigillaria was 

 one of the chief coal-producing plants, and that its 

 fossil casts are found plentifully in all the great 

 carboniferous formations, yet we know comparatively 

 little about its internal organisation, or indeed of 

 its external appearance, with the exception of its 



