NOTES ON CALAMOPITYS. 229 
which he traces a certain resemblance to Calamopitys (Kristophyton) 
Beinertiana. The two genera in question seem to me to come nearest to 
the family Cordaitez, but to belong to a somewhat different branch from 
that which includes Mesorylon and Cordaites. 
The conclusion then, to which our comparisons appear to lead, is that while 
the genus Calamopitys, in the wide sense, belongs as a whole to the group 
Cycadofilices, in the neighbourhood of the Lyginopterides, its more 
advanced species, forming Dr. Zalessky's genus Hristophyton, show some 
approach in certain characters towards the class Cordaitales, and especially 
the family Cordaitez. 
SUMMARY. 
In the first part of the paper additional evidence is brought forward as to 
the course of the leaf-trace in Calamopitys americana. The trace, after 
separating from the reparatory strand, divides into two in traversing the 
zone of secondary wood. It thus differs from the trace of C. Saturni, in 
which division is only completed beyond the zone of thickening. 
The second part of the paper is devoted to a re-examination of the five 
species. 
In C. annularis the zone of primary xylem is almost if not quite continuous. 
The primary xylem-strands are, as a rule, eccentrically mesarch, the 
protoxylem lying nearer the outer side of the strand. Tubular elements, 
which are probably medullary tracheides, are present in the pith, indicating 
a protostelic structure. 
Each leaf-trace strand, on its exit from the wood, is surrounded by its own 
zone of secondary xylem. 
In all these points C. annularis agrees with C. americana. 
In the Halle specimen, a small branch referred by Solms-Laubach to 
C. annularis, the medullary rays are narrow, resembling those of C. fascicularis 
and C. Beinertiana. 
In C. Saturni the primary xylem-strands are found to be completely 
isolated ; there is no continuous xylem-ring. 
The xylem-strands are, as a rule, centrally mesarch, with the centrifugal 
and centripetal portions equally developed. There is little or no indication of 
medullary tracheides. 
The three species, C. americana, C. annularis, and C. Saturni, all had 
Kalymma petioles of very similar structure. 
In C. fascicularis the leaf-trace strands at their exit from the small pith 
are of large size, centrally mesarch and perfectly similar to those of 
C. Saturni. Lower down in their course they diminish in size and the 
centripetal portion of the xylem becomes much reduced. The protoxylem of 
the leaf-trace divides into two in passing through the zone of secondary wood. 
The wood has narrow medullary rays and is generally of a Cordaitean 
type. Its inner layers consist of short, wide tracheides, suggesting a water- 
storing function. 
LINN. JOURN.—BOTANY, VOL. XLIV. U 
