223 



DESCRIPTION. 



G. — E. (?) americana Lesqx. 



Op. tit., Plate lix, figs. 11, 12. 



Following is the description : — 



Eucalyptus americana Lesqx., " Supplement to Annual Report," 1871, p. 7. 



Leaves subeoriaceous, very entire, narrowly lanceolate, gradually tapering upward from below 

 the middle into a long, narrow acumen, narrowed in the same degree to the base, sessile; middle nerve 

 thick, enlarged at the point of attachment; lateral nerves oblique, straight to near the borders, where 

 they join a continuous marginal vein. 



These fine leaves have the nervation and shape of species of this genus. They are comparable, for 

 the nervation at least, to E. oceanica Ung., as figured by Heer (Flor. Tert. Heir., pi. cliv, fig. 14.) In this 

 figure the lateral nerves are more open ; but, in the species represented by the leaves of the " Baltic 

 Flora " of the same author, they are more oblique than in those described here. Since 1871, the time 

 when they were first considered, I have obtained a number of living species from Cuba. Some of these, 

 especially of the family of the Euphorbiacem, Tricera retusa Gray, T. fasciculosa Gris., have a nervation 

 and a texture of leaves exactly corresponding with those of the specimens of Green River, and I now should 

 be disposed to rather refer them to this genus, or at least to the Euphorbiacese, abundant in the subtropical 

 North American flora, than to Australian types ; for this Eucalyptus would be, like the former, an anomaly 

 in the Upper Tertiary flora of the Lignitic. As in species of Tricera, the leaves are very short-petioled, 

 attached to the stems merely, as far as can be seen from the specimen, by the enlarged base of the flat, 

 broad midrib ; the lateral veins, at an angle of divergence of 40°, pass straight to the borders, where they 

 join, with scarcely any curve, a distinct marginal nerve, somewhat thinner than the veins. This apparent 

 marginal nerve is of course formed by the abrupt curve of the lateral nerves which follow the borders, as 

 more distinctly marked in fig. 11. In Tricera retusa, we see exactly the same character, which is observable 

 also in the distribution of the numerous parallel secondary nerves, separated by thinner and shorter 

 tertiary veins, joined either in right angle by nervilles or in very acute angle by branchlets coming out 

 from the midrib or from the lateral nerves. From the fragments figured here, the leaves seem to be 

 comparatively very long, for fig. 11 is twelve centimeters long and fifteen millimeters broad; and by 

 comparison, the fragment represented in fig. 12, which is more than one-third broader, should be part of 

 a leaf about eighteen centimeters long. 



Habitat. — Green River group, Wyoming, above fishbeds.. (Dr. F. V. Hayden.) (Op. cit., 

 pp. 296-7, 1878.) 



B 



