NOTES ON CALAMOPITYS. 227 
No other Cycadofilices seem to approach Calamopitys at all nearly. There 
is a faint analogy in one point between the * Mristophyton” species of 
Calamopitys and Protopitys ; in the latter the leaf-trace strands at the edge 
of the pith have a mesarch structure, with the protoxylem very near the inner 
surface ; traced downwards there seems to be a transition to actual endarchy ; 
there is thus some analogy with the lower part of the xylem-strands in 
C. Beinertiana and C. fascicularis, but in all other respects the structure is 
totally different (Solms-Laubach, 1893). With Stenomyelon, which has 
exarch or nearly exarch xylem-strands, there is nothing in common beyond 
the polydesmy of the petiole (Kidston & Gwynne-Vaughan, 1912). 
It has been pointed out that the Calamopitys series appears to lead in the 
direction of Cordaitales, as shown, not only in the structure of the secondary 
wood in the “ Eristophyton” species, but in the tendency to a dying out of 
the centripetal xylem, shown in the lower part of the course of the leaf-traces 
in those species. We may now enquire how far this advance went, and what 
was the particular direction which it took. 
I am inclined to think that the advance towards a Cordaitalean type of 
organization did not after all go very far. I am chiefly influenced by the 
great size of the primary xylem-strand which constitutes the leaf-trace in 
C. fascicularis and Beinertiana, especially the former*. There are few plants 
even among the Cycadofilices in which the primary wood of the outgoing 
leaf-trace bears so large a proportion to the size of the stele, asin C. fascicularisf. 
It is almost a Filicinean character, and suggests that the leaf which such 
a trace supplied must have been large and very probably fern-like. This 
is certainly a strong argument for C. fascicularis, at all events, having still 
been one of the Cycadofilices. The case is less striking in C. Beinertiana, 
where the stele is so much larger in proportion, but these two species are 
admittedly nearly allied, and what is true of the one must in essentials be 
true of the other, though in C. Beinertiana the leaves may probably have 
been smaller in proportion to the stem. 
For these reasons I should regard the whole series of species here 
included under Calamopitys as having belonged to Cycadofilices, in spite 
of the anatomical advance shown by C. fascicularis and Beinertiana. We 
may still ask whether these species show an approach to any special family 
among the Cordaitales, as at present known to us. 
* Scott, 1902, Pl. 3. fig. 1. 
T There is a physiological difficulty involved in the large size of the outgoing leaf-trace. 
As it dwindled rapidly in the downward direction, how was an adequate water-supply 
maintained ? Possibly the solution is to be found, in the case of C. fascicularis, in 
the presence of the short wide tracheides of the inner layers of the secondary wood (Scott, 
1902, p. 339; Pl. 3. fig. 3). These layers are in immediate contact with the outgoing leaf- 
traces, and appear to be adapted to the storage of water. They may have accumulated a 
supply on which the leaf-trace was able to draw. The storage-layers are the innermost of 
the secondary wood, and may well have been differentiated at a time when the bundles 
supplying the leaves were still actively functional. 
