224 DR. D. H. SCOTT : 
shown by Dr. Zalessky's comparative figures of the tangential sections of 
C. Saturni and J£. Beinertianum (loc. cit. Pl. 4. figs. 6, 7). There is no 
doubt that this is, in most specimens, a real and important distinction ; the 
secondary wood of one of the /ristophyton species, considered by itself, 
would at once be assigned to Cordaiteæ, while that of Calamopitys 
proper would suggest one of the Cycadophyta or Cycadofilices, At the 
same time, if the Halle specimen above described (p. 214) was rightly referred 
by Solms-Laubach to C. annularis, the distinction is inconstant, for in that 
specimen (a small branch) the rays are about as narrow as in an Zristophyton. 
Neither are small and narrow rays by any means unknown among undoubted 
Cycadofilices, Thus in Protopitys Buchiana, they are low and usually 
uniseriate, at most 2-3-seriate in the middle (Solms-Laubach, 1893, 
p. 200, Taf. 6. fig. 4); the same is the case in the polystelie Cladoaylon Kidstoni 
(Solms-Laubach, 1910, Taf. 3. fig. 13) and other species (Solms-Laubach, 
1896, p. 55, Taf. 3. fig. 3). In Pitys the rays seem to be regularly 
multiseriate, and this is here accepted as a generic character; their 
width, however, is extremely variable and in Callivylon, which appears to be 
nearly allied, they are usually uniseriate (Zalessky, 1911, p. 28). 
Another point in the structure of the secondary wood on which Dr. Zalessky 
lays some stress, is the character of the pitting (l. e. p. 26, footnote). He 
finds that in Lristophyton the pits are in regular vertical series, while the 
rows are irregular in Calamopitys Saturni ; in the former they are regularly 
hexagonal in form, while in the latter they are elliptical to hexagonal. "The 
fissures, he says, are oblique or horizontal in Hristophyton, horizontal in 
Calamopitys. I have already, in describing the species, called attention to 
the difference in the pitting. As Dr. Zalessky says, the pits of Calamopitys 
are intermediate between those of Dadoaylon (Cordaiter) and Lyginopteris, 
while in /ristophyton they are typically Cordaitean. The difference is a real, 
if rather a fine one, and is undoubtedly a point in which the wood of 
Eristophyton approaches that of the true Gymnosperms more nearly than is 
the case in Calamopitys proper. 
In fact there is no doubt that the species placed by Dr. Zalessky in 
Mristophyton have made, compared with the typical Calamopitys, a decided 
advance in the Gymnospermous direction, as shown, not only in the general 
structure of the secondary wood, but also in certain features of the primary 
organization. : 
These latter points are not much emphasized by Dr. Zalessky, but seem to 
me to be the most important of all. While in the typical Calamopitys species 
all the primary xylem-strands are more or less uniform in size and similar in 
structure, in the species referred to Kristophyton the strands, as they are 
followed downwards in the pith, dwindle rapidly in size and tend to assume 
an endarch rather than a mesarch structure. In Æ. fasciculare there is 
a near approach to endarchy in the lower part of the strands, while in 
JE. Beinertianum this structure is completely attained. I have never observed 
