WOLVERINE CREEK FLORA. 183 



wolverine creek flora. — These clays and sandy beds of the Laramie have so 

 far failed to yield any evidence of an invertebrate fauna; at least nothing 

 has been found sufficiently well preserved to determine their specific char- 

 acters. Plant remains have been obtained from several of these localities 

 by different members of the Survey, but mainly by Dr. A. C. Gill, who was 

 a member of the field party in the summer of 1887. Although the collec- 

 tion embraces few species, they have proved to be highly important, not 

 only as determining by the evidence of organic remains the Laramie age of 

 these beds, but also as. indicating the geographical distribution of Cretaceous 

 plants and the association of species found in the same strata. 



Prof. F. H. Knowlton, who has studied these plants, has determined 

 seven species, which he has described in detail, with illustrations, in Chapter 

 XIV of this volume. The following is a list of species from the Wolverine 

 Creek beds, extending from the north slope of Pinyon Peak to the low pass 

 at the head of Gravel Creek: Asplenium haguei, Onoclea minima, Paliurus 

 minimus, Sequoia langsfordii, Viburnum rotundifolium, Trapa microphylla, and 

 Paliurus sizxjplioides. 



Of these species the first three are described for the first time by Pro- 

 fessor Knowlton. P. minimus is closely related to P. sisyphoides, a true 

 Laramie species from Black Butte, with which it is here associated. The 

 last four species are also found in the Laramie of Black Butte and Point of 

 Rocks. Asplenium haguei, a small delicate fern, in its relationships is more 

 closely allied to certain Cretaceous species from Greenland than to those as 

 yet recognized from the Rocky Mountains of the United States. Onoclea 

 minima is also closely related to forms from Black Butte and Point of Rocks. 

 The most interesting among these species is Trapa microphylla, which is here 

 represented by several fine specimens. It was first described from Point of 

 Rocks, Wyoming. 



This identification and grouping of plants carries the Laramie flora of 

 central Wyoming, as developed at Black Butte and Point of Rocks, north 

 of its limits as heretofore recognized. The Wolverine Creek beds undoubt- 

 edly belong to the conformable series of Cretaceous sandstones upturned 

 by the orographic movement which took place at the close of the Laramie 

 epoch. They lie near the top of an immense series of sandstones every- 

 where uptilted at high angles. 



