Relation Between Cycadites and Pseudocycas. 337 
From this description of Cycadites Saportce and C. Roemeri, it 
is evident that they agree closely with Nathorst’s specimens of 
Pseudocycas except in the distribution of stomata. As far as living 
members of the Cycadales are concerned, Miss Bancroft (5) has 
shown that this feature is not constant, at least within the genus. 
For instance, Kraus figures stomata from the upper surface of 
Encephalartos Altensteinii, though neither she nor Nestler found 
them in other species; Bornemann records them on the upper 
surface of Zamia muricata var. picta , where she saw none. In the 
present case, there seems to be a series from Pseudocycas insignis 
and P. Steeustnipi, where the stomata are confined to the midrib of 
the lower surface, through Cycadites Saportce where a few additional 
ones appear scattered over the remainder of the lower surface, to 
C. Roemeri where the whole leaf is covered except for the midrib of 
Tkxt-Fig. 1. A, stoma of Cycadites Roemeri in surface view (g, guard-cell; 
d, dorsal thickening ; s, subsidiary cell). B, C, transverse sections of leaf of 
Cyccis sp. in the fresh state (B) and in the dried state (C). 
the upper surface. Nathorst suggests that there may be some 
physiological connection between the boreal habitat of his specimens 
and the restricted stomatal area, since it is shared by Pinus Crameri 
and another conifer from the same region. If so, it is only natural 
that with the more genial English climate should come the enlarge¬ 
ment of the stomatal areas. All the evidence seems to indicate, 
however, that the difference in distribution of stomata is not of vital 
importance, and favours the transference of Cycadites Saportce and 
C. Roemeri to the genus Pseudocycas. 
The next question to arise is the relation of other members of 
the genus Cycadites to Pseudocycas. Where cuticles are unavailable, 
the only criterion is the double midrib. In changing Cycadites 
Dicksoni to Pseudocycas Dicksoui, Nathorst seems to regard that 
character as diagnostic in itself, and on this ground it is not impossible 
