1911] Bartlett,— Ptelea mollis var. cryptoneura 81 
face of the leaves clothed with a soft tomentose pubescence, even when 
old. (Texas, Drummond!)” 
It is obvious that there is scant evidence for considering the two 
names synonymous. If they are, it will be necessary to find another 
name for a plant of the Great Lake region (collected by the late 
Prof. C. F. Wheeler at Saugatuck, Michigan, and by Mr. C. C. Deam 
near Michigan City, Indiana, No. 7087, 31 July, 1910) which is now 
called! P. trifoliata var. mollis T. & G., but which is clearly different 
from P. mollis M. A. Curtis. Under the circumstances, there can 
hardly be any valid objection to maintaining both P. mollis M. A. 
Curtis (excl. syn.) and P. trifoliata var. mollis T. € G. 
In his diagnoses of Ptelea species, Dr. Greene? has laid much stress 
upon the nervation of the samara. “....This seed-bearing body is 
in some [species] marked by rather closely parallel transverse ridges, 
with lines of gland dots running between them, or else the ridges are 
irregularly broken and run into a reticulation, with one or more dots 
in the middle of each mesh. In either instance the ridges may, at 
the edge of the body or a little beyond it, unite to form a wall more or 
less definitely surrounding the body — which wall I denominate 
the cireumvallation — or they may pass directly into the reticulation 
of the wing itself, leaving the body without circumvallation.” It is 
in this character which Dr. Greene calls the “circumvallation” that 
both Ptelea trifoliata var. mollis (Mr. Deam's material from the sand 
dunes of northern Indiana) and P. mollis M. A. Curtis differ from the 
Georgian shrub which is here proposed as P. mollis var. eryptoneura. 
In the one case we have typically “circumvallate” samaras, with 
strongly marked transverse ridges on the body; in the other case there 
seems to be no “circumvallation,” and the transverse ridges of the 
body are altogether obscure. Since Ptelea mollis differs otherwise 
from its var. eryptoneura in merely trivial details, which might well be 
comprehended within the range of fluctuating variability of the 
species, my curiosity was aroused to find out whether or not there was 
actually a structural difference between them. Samaras of both 
types were boiled with caustic potash solution, in order to remove the 
softer tissues from the vascular framework. The two skeletons 
obtained could hardly have been told apart. In both, the longitudinal 
1 Gray's Manual, ed. 7, p. 537. 
?'The Genus Ptelea in the Western and Southwestern United States and Mexico, 
E. L. Greene. Cont. U. S. Nat. Herb. x. part 2 (1906), p. 51. 
