DESCRIPTIONS OF SPECIES. 25 



In this country, as in Europe, the foliage of Glyptostrobus exhibits 

 two forms wherever the plant is found; the short oppressed,, and the longer 

 divergent leaves. In addition to this the specimens from the northwest 

 coast have common character by which they may be distinguished at once 

 from those collected by Dr. Hayden. The Western plant is more slender, 

 the appressed leaves sharper and more delicate, the divergent leaves much 

 longer, corresponding more nearly to the European form described as 

 G. Ungeri, while those from the Upper Missouri resemble more the variety 

 known as G. Europceus. The cones, however, found with the Missouri 

 specimens are more like those of G. Ungeri than G. Euroyxzus, the dorsum 

 of the scale being marked by short, radiating carinse, as in the former, the 

 maro-in being waved, but not regularly scalloped, as in the latter. 



From the extreme West we have as yet no cones which can be cer- 

 tainly referred to this plant, so that the most important element in the 

 comparison is wanting, but it would seem that here, as in Europe, the dif- 

 ferent phases of the plant belonging to the genus Glyptostrobus are so 

 linked together that they should be regarded as forming but a single 

 species. At least we have not yet obtained sufficient material to justify us' 

 in attempting to define the limits of other species. 



The two living species of Glyptostrobus which Fortune found growing 

 in China seem to resemble the fossil forms as much as they do each other, 

 and it is perhaps doubtful whether they should not all be united under the 

 same name. The living and fossil plants are associated with fan-palms, 

 and belong to the flora of the southern temperate zone, or that of a lati- 

 tude ten degrees south of the localities where the fossils occur. 



Formation and locality: Tertiary (Fort Union group). Fort Union, 

 Dakota, and Birch Bay, Washington (Wilkes Exploring Expedition). 



Thuja interrupta Newb. 

 PI. XXVI, figs. 5-od. 



Ann. N. Y. Lye. Nat. Hist., Vol. IX (April, 1S68), p. 42; Ills. Cret. and Tert. PI. 



(1878), PI. XI, figs. 5, 5a. 



"Branchlets flat, narrow, linear, pinnate, opposite, except at the sum- 

 mit of the branch, somewhat remote, connected only by the slender woody 

 axis on which the leaves of the branchlets are not decurrent; leaves in four 



