126 THE LATER EXTINCT FLORAS OF NORTH AMERICA. 



to the summit; lateral nerves pinnate, set at somewhat unequal distances, 

 straight and parallel below, forked and inosculating- above, forming- a festoon 

 parallel with the margin; tertiary nerves forming an irregular network of 

 polygonal and relatively large areoles." 



Collected by Dr. F V. Hayden. 



Of this species there are numerous specimens in the collections made 

 bv Dr. Hayden in as good preservation as the material in which they are 

 fossilized will permit. The nervation is strongly marked, and all its more 

 prominent characters as appreciable in the fossil as they were in the fresh 

 leaves. In nervation, consistence, and outline these leaves are almost un- 

 distinguishable from those of the "Pepperidge" (Nyssa multiflora). The 

 primary and secondary nervation of some species of Magnolia also exhibit 

 a strong resemblance to that of these fossils, but a less complete correspond- 

 ence than Nyssa presents. Without the fruit, or at least leaves preserved 

 in a fine argillaceous sediment in which the finer details of nervation are 

 given, the affinity suggested must be to some extent conjectural. 



Formation and locality: Cretaceous (Dakota group). Blackbird Hill, 

 Nebraska. 



Order SAPOTACE^E. 



Sapotacites Haydenii Heer. 

 PL V, fig. l. 

 Proc. Acad. Nat. Sci. Phil. (1858), p. 265; 111. Cret. and Tert. PL (1878), PL V, fig. 1. 



Professor Heer compares this leaf with one described by him in his 

 Flora Tertiaria Helvetia? under the name of S. mimusops. He further 

 described it as "diminishing toward the base, rounded toward the apex, 

 rather deepty emarginate. From the midrib, which gradually becomes 

 slender and dies out, proceed at acute angles very numerous secondary 

 nerves, which have the peculiarity of ramifjang very much." 



This is one of the leaves described by Professor Heer from tracings 

 sent him by Mr. Meek, and the specimen now figured is that from which 

 the tracing was made. As it has not before been figured, and is frequently 

 referred to in the earlier discussions of the flora of the Dakota group, it has 

 seemed desirable that a figure should be given of it so that it may be iden- 



