260 Bower . — Imperfect Sporangia in certain 
spores, and from their general characters seem to be arrested 
sporangia, rather than young ones in the normal course of 
development : but it is difficult to arrive at certainty on this 
point. The base of this cone is unfortunately incomplete. 
Dr. Scott quotes also a case of a Lepidostrobus in his own 
collection, in which the sporangia ‘ at the top are small, still 
closed, and with thick walls, showing that development has 
been arrested before the absorption of the inner layers.’ 
£ I find the same thing,’ he says, ‘ in my new cone, Lepido- 
ccirpon Lomaxi , as well as in a microsporangiate cone, which 
may probably belong to the same species V It seems more 
common to find the apex of the cone complete, than the base. 
One specimen in Mr. Kidston’s collection (slide No. 98) of 
Lepidodendron Veltheimianum , from Pettycur, shows a gradual 
lessening of size of the sporangia towards the base, but no 
extreme reduction to vestigial proportions was observed. In 
Spencerites insignis 2 a section of the cone c which appears to 
have been made near one extremity of the strobilus,’ shows 
some sporangia of small size : these have been re-examined 
and described by Scott 1 2 3 , who, without being able to locate 
them at the apex or base of the cone, regards them as being 
‘ abortive organs ’ the development of which has been 
c arrested at a rather early stage.’ In Sigillaria the cones, 
which are probably heterosporous, are usually borne on long 
pedicels : the bases of these strobili have been examined in 
a number of specimens in Mr. Kidston’s collection : they show 
gradual transitions from the broad ciliated sporophylls, to the 
smaller, narrower basal bracts : there is no evidence of abortive 
sporangia, which indeed could hardly be expected in specimens 
which are all impressions. But the similarity in external 
appearance to large strobili of Lycopodium or Selaginella is 
sufficiently close to raise the impression that they probably 
existed. 
Speaking of Calamostachys Bimieyana , Williamson and 
1 Extracts from a letter from Dr. Scott. 
2 Williamson, Fossil Plants of the Coal Measures, ix, Fig. 53, p. 341. 
3 ‘On Spencerites,’ Phil. Trans., vol. clxxxix, B, 1898, p. 93, PI. XV, Fig. 15. 
