ART. 19 PLANT AND INSECT FOSSILS COCKEEELL 3 



Green River Eocene Station 2, large excavation with tunnel at 

 head of Salt Wash, Roan Mountains, Colorado, 1922. Also obtained 

 by Mrs. Cockerell at Station 1, on Ute trail. 



This genus illustrates the difficulty of drawing conclusions concern- 

 ing past climates from single species. Lygodiwm is in general a 

 tropical genus, but the living Z. palmatum (Bernhard) Swartz ex- 

 tends north to Massachusetts. 



Family SALICACEAE 



POPULUS WILMATTAE, new species 



. Plate 2, fig. 8 



Leaf broad, with approximately the shape of P. trichocarpa 

 Hooker, length about or nearly (apex missing in type) 70 mm., width 

 71 mm.; base broadly truncate; margins distinctly but feebly and 

 rather remotely dentate, the low obtuse teeth about 2 to 3 mm. apart; 

 petiole about 1.5 mm. thick; midrib and two pairs of lateral veins 

 very prominent, the first pair coming off at the base, the second about 

 3.5 mm. beyond, the latter at an angle of about 45° ; the weak veinlets 

 from the midrib above widely diverging, not far from transverse. 



Green River Eocene, Roan Mountains, Colorado, 1922, Station 2, 

 excavation at head of Salt Wash. Named after Mrs. Cockerell. 



Tlolotijpe.—C&t. No. 36852, U.S.N.M. 



Of all the forms of Populus laiown to me this most resembles the 

 living P. rasumoioshiana Dippel, which I saw growing in Kew gar- 

 dens. The form and appearance are closely similar, but the fossil 

 differs in lacking any really strong lateral veins above the two pairs 

 near the base. Thus the venation, though not the shape, is more like 

 that of the fossil P. zaddachi Heer. 



Family MELIACEAE 



MELIA COLORADENSIS (Knowlton) 



Phyllites coloradensis Knowlton, Revis. Flora Green River Formation, U. S. 

 Geol. Surv., Prof. Paper 131-F, p. 176. 



This appears to be a Melia, related to 31. exjjulsa Cockerell from 

 Florissant Miocene. We obtained it at Station 1, on Ute trail, and 

 Station 2, near head of Salt Wash, Roan Mountains, Colorado. The 

 terminal leaflet may be deeply notched, as Ivuowlton shows one of 

 the lateral ones to be. The leaflets are larger than in M. expulsa, 

 without any serration of the margin. In the living M. azedarach 

 Linnaeus forms occur with the margins of the leaflets nearly entire. 

 Tlie living species inhabit Asia and Australia, The figure of Phyl- 

 lites winch esteri Knowlton looks like a distorted leaflet of this 

 species, but the description entirely negatives such an idea. 



