DESCRIPTIONS OF SPECIES. 37 



Order MYRICACEiE. 



Myrica (?) tripoliata Newb. n. sp. 

 PI. XIV, fig. 2. 



Leaves in threes, lance-linear in outline, acute at summit and base; 

 margins remotely and coarsely marked with appressed teeth; nervation 

 delicate. 



These are leaves which are manifestly distinct from any others from 

 the Dakota sandstones yet described, and are referred to Myrica with 

 doubt, as nothing but the general resemblance of form and marginal 

 serration can be cited as proof of affinity. In due time, however, more 

 material illustrating the species will be discovered, and, we may hope, also 

 the fruit. At present it stands simpty as a positive addition to the list of 

 arborescent plants hitherto found in the Dakota group, but one of which 

 the botanical relations must be determined by future observations. 



Formation and locality : Cretaceous (Dakota group). Whetstone Creek, 

 northeastern New Mexico- 



Order SALICACE^E. 



POPULUS ACERIFOLIA Newb. 



PL XXVIII, figs. 5-8. 



Ann. X.Y. Lye. Nat. Hist., Vol. IX (April, 1868), p. 65; Ills. Cret. and Tert. PI. (1878), 



PI. XIII, figs. 5-8. 



"Leaves long-petioled, broad-ovate in outline, often somewhat three- 

 lobed, obtuse, slightly cordate at base, margins coarsely and unequally 

 crenate; nervation radiate, strong; medial nerve straight, giving off one 

 pair of lateral nerves near the center of the leaf, and above these about 

 three smaller ones on each side. From the base of the midrib spring two 

 pairs of lateral nerves on each side. Of these the lower and smaller pair 

 diverge at an angle of 60 degrees to 70 degrees with the midrib, are nearly 

 straight, give off numerous short branches on the lower side, and terminate 

 in the lateral margin below the middle. The second and larger pair of 

 laterals diverge from the midrib at an angle of about 35 degrees to 45 

 decrees, are straight or slightly curved upward, terminating in the margins 



