knowlton.] DESCRIPTION OF SPECIES. 71 
pers, Wyoming, contains a single example that appears to belong to 
this species. It is not well preserved, and the finer nervation can not 
be made out with satisfaction, but it resembles this more closely than 
any other. It may, however, represent an undescribed species, but it 
must remain for subsequent material to settle this point. 
Habitat. — Near Harpers, Wyoming. Black Buttes, Wyoming. 1 ? 
Boulder County, Colorado. Golden, Colorado (Laramie). 
Viburnum! problematicum n. sp. 
PL XIX, fig. 4. 
Viburnum marginatum Ex., Tert. FL, p. 223, PI. XXXVIII, fig. 2 [non figs. 1, 3-5]. 
Platan it 8 marginata (Lx.) Heer, PI. Foss. Arct., Vol. VII, p. 97, PI. XCVIII, fig. 3 
[non fig. 4, 5; PI. XCIX, figs. 2, 3; PI. CI, fig. 5]. 
Leaves broadly ovate, rounded and wedge-shaped at base, similarly 
narrowed above to an abruptly acuminate apex; margin for the upper 
two-thirds of blade remotely shallow-toothed; petiole slender; midrib 
thin, straight; secondaries four or five pairs, the lowest pair opposite, 
arising at an angle of about 45° a short distance above the base of the 
blade, with three or four branches on the outside which enter the 
teeth; upper secondaries alternate, simple or once- forked, entering the 
teeth ; nervilles very prominent, mainly percurrent at right angles to 
the secondaries or their branches; finer nervation not preserved. 
The leaf figured here is C cm. in length and 4.5 cm. in width, while 
the one figured by Lesquereux in the Tertiary Flora (PI. XXXVIII, 
fig. 2) is about 7 cm. in length and 3.5 cm. in width. They are very 
similar in shape, margin, and general arrangement of nervation, the 
most important difference being the simple upper secondaries in the 
former leaf, as compared with the forked secondaries in the latter. It 
seems hardly justifiable to keep them distinct on this character. 
These leaves are undoubtedly very closely allied to Viburnum? mon- 
tanum, as just described. The latter differs somewhat in shape and in 
the number of secondaries and their origin, but in spite of these minor 
differences it is possible that they should properly be placed together. 
Viburnum marginatum of Lesquereux has long been considered a 
composite species. It is, of course, well recognized that a single tree 
may have considerable variety in size and shape of leaves, but it is 
hardly probable that specific variation in an individual will be as great 
as these drawings would indicate. The larger, broader form (PI. 
XXXVIII, fig. 1) was evidently the one taken by Heer as the basis of 
his transfer of the species to the genus Platanus, but the forking of 
the secondaries is one prominent reason against that reference. This 
is not a Platanus character, and on the whole the leaves do not sug- 
gest that genus. The question of the propriety of referring these 
leaves to Viburnum is also brought up. They may not properly be- 
long there, but they are clearly not Platanus, and are not Viburnum 
marginatum, as originally defined. 
Habitat. — Coalville, Utah. Black Buttes, Wyoming. 
