69 



example — as great an affinity in form and nervation as exists between the 

 Minnesota leaves and those ot Niedershoena, and, therefore, their relation to 

 Ficus is uncertain. 



Habitat. — Cretaceous, (Dakota group,) of Minnesota. Collected in numer- 

 ous fragments by Prof. James Hall. 



Platanus obtusiloba, Lesqx., PI. vii, Figs. 3-4. 



Leaves small, thin, palmately irregularly trilobate ; lobes obtuse, short ; borders undulate ; nerva- 

 tion 3-5 palmate from above the base of the long petioled leaf. 



Platanus obtusiloba, Lesqx., American Journal of Science and Arts, (2), xlvi, 

 1868, p. 97. 



Leaves 6 to 8 centimeters broad in their widest part, not quite as long, 

 round or reniform in outline, enlarged on the side by the diverging obtuse 

 lobes, abruptly narrowed or undulately truncate at the base, which reaches 

 the petiole by a short downward curve ; nervation 3-5 peltate ; the lateral 

 veins at a distance from the basilar border of the leaves, branching ; medial 

 nerve pinnately divided in its upper part ; nervation crespadodrome ; nervilles 

 irregular, deeply marked, some of them simple and continuous. 



In the form of its leaves, and the general character of its nervation, this 

 species is closely related to Anisophyllum semi-alatum, described p. 98. I was 

 even at first inclined to consider all these leaves as representing only one 

 species. There is, however, a marked difference : in the texture of these 

 leaves, which is much thinner in this species ; in their finer, more delicate ner- 

 vation ; in their equal divisions in obtuse undulate lobes, &c. The platanoidal 

 character of these leaves is marked in the branching of the primary veins at 

 a distance above the borders, and, therefore, they are not referable to Acer, 

 some species of which have leaves of an analogous form. 



Habitat. — Beatrice, Gage County, Nebraska, Hayden. Represented by a 

 number of specimens. It may be remarked that all these specimens were 

 found at the same locality as those of Anisophyllum. Considering the great 

 affinity of characters, this coincidence tends to indicate identity of species, or 

 at least a community of habitat for closely allied, perhaps transient or derived 

 forms. 



Platanus pkim^va, Lesqx., PI. vii, Fig. 2 ; PL xxvi, Fig. 2. 



Leaf large, palmately trilobate, with short, scarcely distinct lateral lobes, broadly deltoid, deeply 

 distantly dentate to the point, truncate undulate to the base; nervation three-palmate, platanoidal. 



