284 UNITED STATES GEOLOGICAL SUEVEY— TERTIARY FLORA. 



Tertiary formations, twenty-one species, described either from leaflets only, 

 or from leaves and fruits found together, or from fruits alone; and, besides, 

 six species o{ Pterocarya. 



At the present time, one species only of Juglans is known. Its leaflets 

 liave the borders entire. It is the noble J. regia, Linn., which, by cultiva- 

 tion in Middle and Southern Europe, has given numerous varieties, all bearing 

 fruits, known everywhere as palatable and nutritious food. In its wild state, 

 it inhabits the trans-Caucasian provinces of Asia. In the section of the 

 serrate leaflets, Jug/ans has three well-known species: J. nigra, Linn., J. 

 cinerea, Linn., of the Eastern United States of North America, and J. mpestris, 

 Engelm., indigenous in New Mexico; a fourth species, whose fruit resembles 

 that of the Butternut, is found in AsiaticEussia. In the genus Carya, all the 

 living species, nine, belong also to the eastern slope of this continent. One 

 only, which is mentioned as not satisfactorily known, belongs to Mexico. 

 From this, it is evident that there is in Europe an anomaly of distribution in 

 considering the numerous species there known from the Tertiary, while none 

 at all is left in the flora of that continent. In North America, species of 

 Juglans are already represented in the Eocene o.f Golden, Black Buttes, Spring 

 Canon, etc., mostly l)y leaflets with entire borders, more numerous still at 

 Evanston and in the Green River group. Of the section of dentate leaflets, 

 two species have been described from the Eocene of the Mississippi; none, 

 however, from that of the Rocky Mountains. They appear first in the 

 Evanston group, and continue in an increa.sing proportion upward, while those 

 of the other section become less preponderant, as evinced in the Pliocene of 

 California, where one species only of this last section is present, while it has 

 four distinct ones with denticulate or serrate leaflets. This seems like a 

 premonstration of the present character oi ouv Ji/glandinets, which all have 

 dentate or serrate leaflet.*;, and of the future preponderance of their species. 



JUGLAKS, Linn. 



§ L — Leajlets entire. 



J u g: I » II s r li a inn o i d o s , LeBqz. 



Plate LIV, Figs. 6-9. 



JiigJans ilianmoides, Lesqx., Animal Report, 1871, p. '294 ; 1872, pp. 382, 400, 402. 



Leaves oval, narrowed in a curve or ronniled to the petiole, very entire; K-iter-al nerves tbin, 

 distant, curved in passing to the borders, camptodrome. 



The leaflets are apparently taper-pointed or acuminate, very variable in 

 size, like all those referred to this section ; the lateral nerves averaging 40'^ of 



