PENHALLOW | A REPORT ON FOSSIL PLANTS 297 
main, they are much better preserved. That this genus has already 
been recognized as an element of both the Cretaceous and Tertiary 
floras, has béen shown on former occasions, and especially by the occur- 
rence of C. dawsoni, Penh., in the Eocene of the Great Valley and 
Porcupine Creek Groups, as well as in the Cretaceous of the South 
Saskatchewan, near Medicine Hat (47). This extended geological 
range is quite in harmony with the idea that the genus as a whole is 
an old one, and that the present species is ancestral to, if not in all 
respects identical with the existing C. macrocarpa. 
= ULMUS PROTORACEMOSA, 0. sp. 
Plates IV-VI 
This plant is represented by a single specimen of calcified wood, 
the structure of which is fairly well preserved, chiefly with respect to 
the transverse section. In the longitudinal sections the structure is so 
altered that many of the essential details cannot be determined, and the 
final diagnosis must be deferred until such time as more ample and more 
perfectly preserved material renders it possible to draw it accurately. 
The provisional diagnosis nevertheless shows this wood to be that of an 
elm. While the wood of this genus is not known in horizons earlier 
than the Pleistocene, in which formation both U. americana and U. 
racemosa are well recognized types, the present material affords the 
first definite knowledge of the woody structure of a genus in formations 
where its leaves have been known for some time. Among existing 
species this wood is probably most nearly comparable with U. race- 
mosa — a species which exhibits great structural variation along lines 
essentially parallel with those shown in the present case. From the 
details of structure available, it is perhaps not unsafe to assert that 
the resemblance is so close as to justify regarding the fossil as the 
prototype of that species, and it is therefore named with reference to 
this fact. The diagnosis so far as obtained is as follows :— 
ULMUS PROTORACEMOSA, n. sp. 
Transverse.—Growth rings very variable and with no obvious distinction of spring 
and summer wood; in stems of rapid growth very broad and showing 
a gradation of vessels and wood parenchyma; in stems of slow growth 
very narrow and more variable.. Structure rather dense in the 
greater portion of the ring; the wood cells medium, rather thick- 
walled. Vessels of the spring wood medium, not very large, radially 
oval or oblong and often so disposed as to be radially 2 seriate but 
without thyloses; forming about 12-14 the thickness of the ring 
and abruptly replaced by small vessels and wood parenchyma forming 
