148 DESCRIPTION OF SPECIES. 



The leaves are small, 2i to 5J centimeters long, enlarged toward the 

 upper part; the areolation is distinct, formed by nervilles crossing the 

 oblique divisions of the lateral nerves at, right angles. 



/M— Florissant. U. S. Geol. Expl. Dr. F. V. Hayden. 



Myrica nigricans, Lesqx. 

 " U. S. Geol. Rep.," vii, p. 132, pi. xvii, fige. 9-12. 



Myrica Bolandcri, Lesqx. 

 Ibid., p. 133, pi. xvii, fig. 17. 



Myrica undulata, Lesqx. 

 Ibid., p. 131, pi. xvii, fig. 5. 



Leaves lobate; lobes irregular, often serrate. 

 § 2. Leaves pinnately lobed ( Comptonia). 



Myrica partita, Lesqx. 

 Ibid., p. 134, pi. xvii, fig. 14. 



Myrica diversifolia, sp. nov. 

 Plate XXV, Fige. 6-15. 



Leaves membranaceous, short-petioled, either longer, deeply lobate and lanceo- 

 late, or shorter, broadly ovate, diversely tri-quadri-lobate; lobes dentate; primary 

 nerves narrow, the secondary open, curved in passing to the points of the lobes or of 

 the teeth, branching; tertiary nerves in the direction of the sinuses, forking under 

 them, each branch following the borders. Seeds small, oval-acute. 



At first it is difficult to see that these leaves are referable to the 

 genus Myrica and that they all represent the same species. In compar- 

 ing, however, fig. 6 to Myrica (rrceffii, Heer, "Fl. Tert. Helv.," iii, p. 176. 

 pi. cl, figs. 19, 20, the character of the nervation, the form of the leaves, 

 the dentate lobes will be found much alike. The species are far different 

 but the type is the same. The same degree of affinity is remarked between 

 figs. 11-13 of our plate with Myrica latiloba, Heer, figs. 12-15 of the same 

 plate; there is also a marked degree of relationship between the leaves I 

 refer to this species and Comptonia laciniata, Ung., "Fl. von Sotzka," 

 p. 31, pi. viii, fig. 2. 



Comparing now with one another the fragments which represent this 

 species, we see in fig. 8 the same characters exactly as in fig. 6, merely 

 modified by the shortening of the leaves and. of their lobes. Fig. 11 rep- 

 resents an intermediate form, and with its deep-cut lobes fig. 13 is like an 

 original representation of fig. 11. Indeed, considering the characters of 



