of Bennettites gibsonianus , Carr. 425 
proved to be a genuine stem of Cycadeae. This further shows 
how precarious is the identification of fossil remains when it 
rests on superficial characters only. 
It was observed as early as 1851 by R. Brown 1 that while the 
transverse section of all stems from the dirt-beds of the Island 
of Portland is circular, that of the stems from the Isle of Wight 
is distinctly elliptical. This difference is seen most plainly in 
the pith and ring of wood, and can hardly be attributed to 
subsequent compression. Carruthers has employed it to dis- 
tinguish his Bennettiteae into two genera ; Bennettites , Carr., 
containing the specimens with an elliptical transverse section ; 
and Cycadoidea , Buckl., in which the section of the stem is 
circular. I do not believe that this distinction will be main- 
tained, for among the specimens found in Italy and preserved 
in the Museums of Bologna and Imola, we find, besides the two 
types above-mentioned, others which are almost circular, and 
show only a very slight compression. I should therefore 
rather confine the name Bennettites to the species in which we 
know the characters of the fructification, that is to B. gib- 
sonianus, Carr. Among the Italian specimens there will perhaps 
be found some forms resembling B. gibsonianus , and requiring 
to be placed with it ; all the rest, which have only the basal 
portion of the fruiting shoot, may for the present be properly 
included under the name Cycadoidea , Buckl., whether their 
transverse section be round or elliptical. At the same time I 
do not propose to carry out this nomenclature, which would 
have been suitable enough in the beginning, but now, whilst we 
are still awaiting the final determination of all the facts of the 
case, would merely have the effect of increasing the synonymy, 
which is already sufficiently difficult. 
Carruthers’ account of the structure of the fructification of 
his Bennettites gibsonianus has often been misunderstood. It 
is really a very apt description of the fossil, but it is so concise 
that to understand it thoroughly requires very careful study 
and constant comparison of the figures. There are also some 
obscure points here and there which the author could not at 
1 See Carruthers, loc. cit., p. 694. 
