DESCRIPTION OP SPECIES— ULMACE^. 189 



at the base, with larger, less mixed teeth, and a longer petiole. Except by the 

 more curved lateral nerves and the simple unequal teeth, these fossil leaves 

 could represent a variety of TJlmus Americana like the one growing in Texas, 

 which has small, either equal or inequilateral leaves, round or cordate at tlie 

 base. 



Habitat. — Near Middle Park, Florissant, Colorado (Z>/-. F. V. Hayden). 

 Castello's Ranch, Colorado {Capt. E. Berthoud). 



PLANERA, Gmel. 

 This genus is closely allied to the former. Its only living species, indig- 

 enous in the southern part of the United States, has been found by Michaux 

 along the borders of the Lower Ohio River, where it is very rare, more 

 generally inhabiting the swampy bottoms of Georgia, Florida, etc. This spe- 

 cies, Planera nquatica, Gmel., is a small tree resembling Carpinus, bearing 

 along its branches small, ovate-pointed, unequally serrate leaves, distichous, 

 and penninerved, like those of Ulmus. The genus is recognized in the 

 Miocene of Europe in two species, one of which, P. Ungeri, Ett., is very 

 common and variable. In the geological formations of this continent we have 

 already three species, one in the Middle Miocene, PL microphylla, Newby., 

 the others described below in the upper stages of the same formation. I have, 

 besides, mentioned from Bellingham Bay, P. duhia, Lesqx. (Am. Journ. Sci. 

 and Arts, vol. xxvii, p. 361), probably a small form of P. Ungeri, and discov- 

 ered leaves referable to the living species (P. aquatica) in the chalk banks, 

 Pliocene, of the Mississippi River, as remarked in the same volume, p. 365. 

 We may therefore follow the distribution of Planera from the Vancouver 

 Eocene and the Fort Union JHocene, as indicated by Dr. Newberry, without 

 interruption, to our time. 



Planera longifolia, Lesqx. 

 Plate XXVII, Figs. 4-6. 

 Planera longifoUa, Lesqx., Annual Report, 1872, p. 371 ; 1873, p. 413.— Schp. Pal. V^g6t., iii, p. 592. 



Leaves small, comparatively thick, oblong, lanceolate, obtusely pointed, cuneate to the petiole, 

 simply obtusely dentate ; lateral veins thick, simple, craspedodrome. 



The species is represented by a large number of specimens, all with the 

 same characters. The leaves vary in size from two and a half to four and a 

 half centimeters long without the petiole (five to eight millimeters long) and 

 from nine to eighteen millimeters broad in the middle. Fig. 5 represents the 

 broadest of all the leaves seen as yet. They are oblong, obtusely pointed, 



