24 BOTANICAL GAZETTE [JANUARY 
of Brongniart with favor, but regards a different form as more 
expressive of the relationship which he determined.* He 
therefore says: ‘‘ Pour conserver le nom, premier en date, donné 
par M. Brongniart a ces portions de plantes, et en méme temps 
pour rappeler leur nature, je les designerai sous le nom de 
Myelopteris.”’ 
The yet more recent studies of these plants by Williamson 
led him to admit the force of the arguments employed by 
Renault and the appropriateness of his name. Reference to 
Williamson’s figures discloses several points of resemblance 
between his specimens and my own. This is to be noted first 
ina great similarity with respect to the general distribution of 
tissues, particularly as exhibited in his figs. 3 and 4, as likewise 
in the very general removal of the vascular bundles. The vas- 
cular bundle given by him ( Williamson, fig. 7*) is closely similar 
to that derived from the Topeka specimen (fig. 4), but differs 
materially from his other representation (Williamson, fig. 7) 
taken from the upper end of a rachis, which is closely similar to 
bundles observed by me in Dioon edule, whereby it offers some 
basis of comparison with the Cycadacez. 
In longitudinal section the resemblance is ‘rather close, but 
in this aspect the Topeka specimen offers little evidence of a 
satisfactory nature beyond the general. relations of parts, and 
- the structural markings of the vessels which are seen to be 
scalariform, as in the ferns. 
Finally, the relation of the mucilage passages to the vas- 
cular bundles (Williamson, fg. 74) and of the very large, ellip- 
tical mucilage passages to the sclerenchyma strands (William-_ 
son, fig. 13), as also the very thin walled elements of the funda- _ ny. 
mental structure, all present features almost identical with those 
observed in the Topeka specimens (figs. 1, 2, 3). 
Williamson’s specimens appear to differ from my own chiefly 
with respect | to the particular distribution of the sclerenchyma | 
strands in the cortical region, a difference which, however, is 
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