222 DR. D. H. SCOTT: 
a. C. fascicularis. Pith small, with no sclerotic nests. 
Smaller xylem-strands embedded in the pith, with their centripetal 
xylem much reduced. 
B. C. Beinertiana. Pith large, with conspicuous sclerotic nests. 
All xylem-strands in contact with secondary wood. Centripetal 
xylem dying out in the smaller strands, which thus become endarch. 
The course of the leaf-trace has not been included in the synopsis as it is 
only adequately known in the two species C. americana and C. Saturni; in 
the former the first division of the trace takes place in the zone of thickening ; 
in the latter not till the trace has passed beyond this zone. 
Affinities of the Species. 
We have now to consider the relations of the species among themselves 
and especially the question of the division of the genus, proposed by 
Dr. Zalessky. As mentioned above, this author separates the two species, 
C. fascicularis and C. Beinertiana, under the generic name LEristophyton, 
leaving in the original genus C. Saturni and C. annularis ; to these the new 
species C. americana must now be added, as its close affinity with C. annularis 
is beyond dispute. 
Dr. Zalessky, indeed, goes beyond generic separation, and while admitting 
a certain analogy and even phylogenetic relation between Calamopitys and 
Zristophyton * (Zalessky, 1911, p. 27) he points out that the former shows 
clear affinity to Lyginopteride, with some approach to Medulloseze also, but 
that no such proximity to Lyginopteris t or, in general, to the Cycadofilices 
is found in the species referred to Zristophyton (l.c. p. 24). The question at 
issue is thus an important one and not merely a matter of the definition of 
genera. 
In support of his contention Dr. Zalessky brings forward a number of 
arguments of very unequal value ; while some are of undoubted weight and 
interest, others are trivial or based on a misconception of the facts. 
The author goes so far as to state that except for the mesarch xylem-strands 
everything in the two groups which can be compared appears to differ 
(10. ps 29): 
To clear the ground it may be well to deal first with the less important 
arguments, reserving for later consideration the more weighty matters on 
which I am to a certain extent in agreement with Dr. Zalessky. 
He points out that the xylem-strands are rarely embedded in the pith 
in Calamopitys Saturni, while all the smaller strands are so embedded in 
* For the sake of clearness I provisionally adopt. Dr. Zalessky's nomenclature in discussing 
his position. 
+ Lyginopteris, Potonié, is the equivalent.of Lyginodendron as used by Williamsou and 
formerly by myself, 
ae eC s 
ii: 
