60 



scarcely any diminution in their thickness ; they are joined by perpendiculai 

 distant subcontinuous nervilles forming large areas, with a close, nearly square 

 areolation. I have referred to the same species the leaf of PI. xxiv, Fig. 4, 

 with some doubt. The form is the same, as also its thin substance ; but it 

 bears under the lowest pair of lateral veins a distinct marginal one, and the 

 lateral veins are more divided than in the normal form. These differences 

 do not appear marked enough for authorizing a separation. 



Habitat. — Lancaster County ; Decatur, Nebraska, Hayden. The speci- 

 men of PI. iii comes from this last locality, where I found it with other 

 fragments of the same species. 



Salix prote^folia, Lesqx., PI. v, Fig. 1-4. 



Leaves lanceolate, taper-pointed, largest at or more generally below the middle, coriaceous; sur- 

 face polished. 



Salix proteafolia, Lesqx., American Journal of Science and Arts, loc cit., 

 p. 94. 



The size of these leaves is very variable, from 5 to 12 centimeters long 

 and 1 to 2 centimeters broad, generally lanceolate and gradually tapering to 

 the point from a little above the base where they are the largest, and descend 

 by a more or less tapering outward curve to a short petiole ; some of the 

 leaves, however, as seen in Fig. 2 and 4 are wider in the middle, and judging 

 from the last figured leaf, the smallest, the form is sometimes oblong oval 

 and the point blunt. The speeies is represented by a number of leaves, 

 some crowded upon the same specimens and indentifiable, though fragmentary 

 they may be, by their thickish texture and polished surface. For this reason 

 I have considered them all representing a single species, though different the 

 outlines and size of the leaves may be. From their form, and especially their 

 nervation, which is marked Fig. 3 as distinct as it could be seen, these leaves 

 are truly referable to Salix, and merely considering these characters, they 

 could not be separated from Salix tenera, A. Br., as figured and described by 

 Heer, Flor. Tert. Helv., (p. 32, PL lxviii, Fig. 7-13.) The variety in the 

 form of the leaves enlarged in the middle or above the base ; in their size, 

 even in the nervation, is exactly the same. 



The remark of Schimper, (in Pal. Veget., vol. ii, p. 663,) that if the 

 relation of some saliciform leaves of the Cretaceous formation is rightly ascer- 

 tained we have here one of the oldest forms of the Angiosperm dicotyledonous, 

 is, with its restriction, applicable to every kind of fossil vegetable remains 



