NOTES ON CALAMOPITYS. 211 
respects the xylem-strands of C. annularis agree with those of C. americana 
(see Phots. 2 & 4; also Scott & Jeffrey, 1914, Pl. 35. figs. 1, 2, 4; Pl. 36. 
fig. 9). In other strands the structure is less eccentric, and there is 
correspondingly less differentiation between the inner and outer portions 
of the xylem (Phot. 14). The xylem-strands which are in closest contact 
with the secondary wood have the most eccentric structure; conversely, 
those which are more nearly centrally mesarch stand a little further back, 
and even, in some cases, appear to be separated from the secondary wood by 
a layer or two of parenchyma. 
It was mentioned in the paper by Prof. Jeffrey and myself (l. c. p. 326) 
that there is evidence for the occurrence of medullary tracheides in 
C. annularis, as in C. americana, I have carefully looked into this question. 
In transverse sections one can distinguish at a few places elements with. 
thicker walls than the ordinary parenchyma, and resembling the tracheides 
of the xylem-ring. But the preservation is not such as to make these 
indications at all convincing. The longitudinal section of specimen 97 
passes through the middle of the pith as shown by the dimensions. Several 
tubes are seen embedded in the medullary parenchyma; they are of very 
various diameters, ranging from about 100 to about 360 u —the larger are 
probably distorted (Phot. 15). The smaller tubes agree very well in shape 
and dimensions with those in the pith of C. americana (Scott & Jeffrey, 
1914, Pl. 34. Phot. 51; Pl. 36. fig. 8). These tubes appear to have a wall 
of their own (Phot. 16), but pits have not been observed. There is a strong 
presumption that these elements are medullary tracheides, but better evidence 
is required. — Similar tubes occur in the pith of the only other specimen 
under the name C. annularis of which I have a radial section. This will be 
described below. 
As regards the secondary wood there is not much to be said. The 
medullary rays are multiseriate, but not dilated outwards (Phot. 12). In 
radial section they are muriform, with narrow cells. The secondary 
tracheides are much smaller than the large elements of the primary xylem— 
about 60 p in the former to 100 w in the latter. The radial section shows 
the pits in 3-6 series; the arrangement in horizontal or slightly oblique 
ranks is fairly regular ; longitudinally, the pits may either be alternate or 
in irregular vertical series. Their form is commonly somewhat elliptical 
or at least elongated in the transverse direction. In all these respects 
the structure agrees with that of C. Saturni and C. americana, 
The sections at my disposal give little information as to the mode of exit 
of the leaf-traces. In specimen 97 there is at one point a disturbance in the 
regularity of the wood, no doubt connected with a leaf-trace (see Phots. 11 
and 12). Two segments of the secondary wood are somewhat prominent, 
with a convex outer edge; between them the tissue is badly preserved, but 
there was evidently a median wedge of wood, not extending so far out us its 
