PLANTS FROM ALASKA. 169 



palmata Heer and figured in his paper. pL xvi, fig. 5. It. however, 

 shows no trace of a division of the lamina of the leaf. The other, given 

 in PI. XLIV. Fig. 3. was obtained by Mr. Dumars. Both give the basal 

 parts with a portion of the petiole. These leaves lack their temiinal 

 parts. They narrow gradually to a wedge-shaped base and expand to 

 a fan shape in the opposite du'ection. They show no division of the 

 lamina in the parts preserved, but may higher up have Ijeen palmately 

 divided. The base, in its prolonged wedge shape, differs from the 

 Ginkgo leaves associated with these forms, but the principal difference 

 is in the nerves. These are shown with some distinctness in PI. XLH'. 

 Fig. 3. Fig. 4 shows the nature of the nerves. The margins are thick- 

 ened to forni a parent nerve that sends ofi". veiy ol)lic[uely, secondary- 

 nen^es that enter the lamina of the leaf. They fork at then* insertions 

 and then are mostly single. Occasionally at long inter\-als a second 

 forking occui"s. but this is ^•ely rare. The branches are approximately 

 parallel, diverging slightly in ascending in the leaf. They are quite 

 strong. The nerves of the central part of the leaf ascend from the top 

 of the petiole. In many respects these leaves are like the genus Ginkgo- 

 dium, established l^y Yokoyama for certain forms from the Jurassic of 

 Japan." But the Japanese plants have slender nerves that do not fork 

 at all. They go off from the marginal nerve straight to the summit 

 of the leaf and are parallel to the axis of the leaf. As, however. Yoko- 

 yama found only one species, it is possible that the limits of variation 

 of the genus may include the Alaskan species. 



This fossil resembles also the forms described from the Permian 

 of southwest Pennsylvania and West Mrginia as Saportsea.*' This has 

 the marginal nerves and the branching lateral ones, but the difterences 

 are too gi'eat to pennit these leaves to be placed in that genus. The 

 material is so imperfect and small in amount that the Alaskan fo.ssil 

 can not be positiveh' identified with Ginkgodium. 



" Jurassic plants from Kaga.etc: Jour. Coll. Sci. Imp. Univ. Japan. Vol. Ill, Pt. 1. pp. .56-58. pi. ii.fig 4e: 

 pi. iii, fig. 7: pi. viii; pi. i.x. figs. 1-10. 10a: pi. xii, figs. 14. 1.5. 



6 The Permian or Upper Carboniferous flora of West Virginia, by Wm.M. Fontaine and I. C. White: Second 

 Geol. Survey Pennsylvania. Report of Progress, PP. ISSO, pp. 99-103, pi. x.^ixriii, figs. 1-1. 



