444 CASH : FOSSIL FRUCTIFICATIONS OF YORKSHIRE COAL MEASURES. 
''J'ai d^ja fait observer plus haut que le Volhnannia sessilis, 
Presl, le Calamodendron commune? et VAderophyJlites lonyifolia, fiour^s 
d la pi. VL, du memoire de M. Binney, appartiennent a VAnvulnria 
longi folia." 
On the 19tli June, 1873, Professor ^Y. C. Williamson read his 
fifth paper " On the Organization of the Fossil Plants of the Coal 
Measures," in which he discusses " the relations subsisting between 
certain stems described by him, and the numerous fruits that have 
been described and figured by various observers on previous occasions." 
And he there contends " that the only British strobilus, of which 
the internal organization has hitherto been described, that has any 
claims to be regarded as the fruit of Calamites, is that which I 
figured in the fourth volume of the ' Transactions of the Manchester 
Literary and Philosophical Society,' " this contention and the Pro- 
fessor's expressed views on the structure of this strobilus have been 
very recently fully confirmed, and are fully expressed in his last 
memoir, On the true Fructification of the Calamities." Org. of Foss. 
Plants of C. Mea3., Pt. XIV., Phil Trans., London, 1888. The 
learned Professor's views on the relation of the fruit spike of 
Calamostachys Binneyana to Equisetum and CaJarnites are thus sunnned 
up. After balancing these various facts and arguments, I am led 
to the conclusion that Calamostachys Binneyana has much closer 
affinities with Asfemphyllites than with Calamites. With the latter it 
has no one structural feature in common. There is no solitary point 
in which the two plants resemble each other. The resemblance of 
the fertile sporangia of Calamostachys to those of Equisetum, has been 
combined with the foregone conclusion that the Calamites w^ere 
Equisetaceous plants, in leading to the belief that the two were parts 
of the same plant ; but I cannot conceive of any conditions in which 
the stem of a Catamite could be prolonged into that of the Calamos- 
tachys. I have carefully investigated the relations which the fertile 
stems of Equiseta bear to axes of their terminal fruit spikes, and I 
find that their respective structures are typically identical. The 
transition from the stem to the fruit-axis produces no structural 
changes save such as are of the most trivial kind ; the general type 
remains unaltered and continuous. But to place Calamostachys 
