242 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



AMPELOP'SIS. Michx. 



As this genus is only represented at our time by the beautiful Virginian 

 Creeper, the North American A. quinquefolia, Michx., the presence of one 

 •species, similar to, if not identical, by the characters of the leaves, with the 

 living one, is a remarkable coincidence, which should not be overlooked in 

 the historical records of the present flora. The geological floras of Europe 

 have not, to this time, any fossil species of this genus. 



Ampclopsis tertiaria, Leaqx. 

 Plate XLUI, Fig. 1. 

 AmpelopsU tertiaria, Lesqx., Supplement to Annual Report, 1871, p. 7. 



Leaf digitate, with five oblong-lauceolate leaflets, gradually narrowed downward to a short, 

 Blightly winged petiole, distinctly and distantly serrate; secondary nerves camptodrome, entering the 

 teeth by lateral branches or nervilles. 



The nervation of this leaf is similar to that of the leaves of A. quinque- 

 folia. The only difference remarked between the fossil and the living 

 species is in the form and size of the leaflets, which in the fossil plant are 

 smaller, narrower, or less distinctly acuminate, and decurring at the base to 

 the short petiole. As in considering a large number of leaves of the Virginian 

 Creeper, it is not very easy to find two of them perfectly similar by the shape 

 of the leaflets, their nervation, and the size of the border teeth, it seems 

 impossible to point out a peculiar character of the fossil species which could 

 not be recognized in some specimens of the living plants. 



Habitat. — Green River, Wyoming, above fish-beds {Dr. F. V. Hayden). 



CORNER.. 



CORNUS, Tourn. 



In the present flora, this genus is mostly represented by North American 

 species ; for nine of these are described in Gray's Flora of the United States, 

 and six in that of California. Half a dozen species are credited. to Asia, one 

 to Europe, and one to Mexico. The genus also appears (o be of recent origin ; 

 for no fragments of leaves referable to Cornus have been discovered in any 

 of the Cretaceous formations, either of Europe or of this country. The Euro- 

 pean paleontologists have described fourteen Tertiary species, one only from 

 the Eocene of Suzanne, all the others Miocene, ranging in their distribution 

 above the 45° of latitude ; one found also in Greenland, and another as yet 

 limited to Spitzbergen. In this country, the species described below are from 



