142 UNITED STATES GEOLOGICAL SUltVEV— TEKTIAKY FLOKA. 



extremity is more marked. The inequilateral shape of the leaves aud the 

 irregularity of nervation are not of frequent occurrence in the living species of 

 Alnus; these characters are seen, however, in the leaves of a number of fossil 

 species, like Alnus cychidum, Ung., A. sporadum, Saj)., A. cardiophylla, etc. 

 Habitat. — Alkali Station, Wyoming {IVm. Clehurn). 



CUPULIFER^. 



OSTRYA, Michx. 



By their form and nervation, the leaves of this genus resemble those of 

 Carpinus and Betula. The teeth of the borders are smaller than those of 

 Carpinus, and they do not bear any secondary teeth upon their anterior face. 

 As yet, we have no fossil remains referable to this genus in the North Ameri- 

 can fossil floras. The capsule of the fruit, which is veined in its length and 

 vesicular, is easily recognized, though the leaves may not be distinct from 

 those of Carpinus. In the European Tertiary Flora, the genus Ostrya is 

 represented by six species, one of them Eocene, another of doubtful refer- 

 ence; the others all Miocene. The present flora has only two species, one 

 eastern, in southern Europe, extending from France to the Lebanon Mount- 

 ains; the other, O. Virginica, exclusively belongs to this continent, having 

 also a wide range of distribution, or from New Brunswick to Lake Winnipeg, 

 in 30° of longitude, and from 55° of latitude north to 20° in Mexico, where 

 the species has been found near Jalapa, and still more south, in the mountains 

 of Orizaba. It is, therefore, probable that one species, at least, of Ostrya 

 may be found in the American Tertiary. 



CARPINUS, Linn. 



The geological distribution of this genus does not agree in Europe 

 and in North America, as far as we know it, at least. While here two spe- 

 cies only are known by their leaves, from specimens obtained in the Upper 

 Miocene of the Parks, the paleontologists of Europe have described seventeen 

 species from leaves, and eight from the fruits or from involucres. It is pro- 

 bable, as Schimper supposes, that a number of these species will have to 

 be eliminated by more careful researches. However, the predominance of 

 this genus is marked in a high degree in Europe in com])arison to what it is 

 here. The genus appears already in the Eocene of Sezanne by the leaves 

 of two species; the others are Miocene; only one is referred to the Plio- 



