58 BULLETIZSr 16 9, UNITED STATES NATIONAL, MUSEUM 



ton concludes that the beds are Fort Union. Incidentally this is 

 some sUght evidence that these upper beds are still in the Paleocene, 

 but this perhaps cannot be taken very seriously. 



It seems probable that the Fort Union flora of this field is closely 

 similar to that of the Bull Mountain field (lists in Wooisey, Richards, 

 and Lupton, 1917) and also to the very large and well-known flora 

 of the Glendive area (lists and references in Knowlton, 1919), in short, 

 that it is the typical, wide-ranging Fort Union flora, which seems to 

 have shown little geographic or stratigraphic differentiation from 

 Upper Cretaceous to Upper Paleocene and throughout the West. 

 Leaves are found at almost all levels and throughout the field, although 

 really well-preserved specimens can seldom be recovered. Specimens 

 apparently of the handsome species Platanus nobilis were particularly 

 noticeable in the sandstones stripped from above the bone layer 

 in the Gidley Quarry. The general occurrence of leaves here and 

 elsewhere in the field suggests that the whole region was heavily 

 forested, chiefly by deciduous trees, during much of or all the Paleo- 

 cene. It demonstrates the presence of a M^ell-developed arboreal 

 habitat and of abundant food for browsing and frugivorous animals 

 and suggests (but by no means proves) that the more open type of 

 plains habitat was here relatively restricted or absent. 



Knowlton (1927, pp. 184-186) has summed up the Fort Union 

 flora in general, and probably liis remarks apply in large measure to 

 the i^lants of this field throughout Lebo and Melville time. About a 

 dozen species of small ferns and the sensitive fern Onoclea are known, 

 as well as horsetails, "a beautiful little selaginella", and abundant 

 grasses and sedges. Only one palm, and that rare, is recorded. "It 

 was, however, a very large-leaved fan-palm, showing that conditions 

 were not altogether unfavorable." Conifers are abundant, with 

 three sequoias, a yew, bald cypress, two or three pines, and an arbor- 

 vitae that was particularly abundant. There is a rare ginkgo. The 

 most conspicuous and abundant dicotyledonous trees were poplars, 

 with leaves suggestive of the quaking aspen. Sycamores also were 

 abundant, some with very large leaves. Viburnums were also very 

 common and were "presumably small trees or shrubs, known at the 

 present day as arrowwood, blacldiaw, tree cranberry, etc." There 

 were also oak, alder, chestnut, hazelnut, maple, elm, magnolia, hick- 

 ory, walnut, birch, beech, ampelopsis, bittersweet, and rare figs and 

 laurels. 



Invertebrates. — Mollusks occur throughout the field and often in 

 extraordinary abundance. The majority of them are fresh-water 

 mussels and gastropods, although a few may be terrestrial snails. 

 The common types are several dift'erent species each of "Z7mo", 

 Viviparus, and Campeloma. A large collection from just below the 

 Lebo has been hsted page 17. Dr. Russell has also identified the 



