Ch. XV.] 



UPPER MIOCENE STRATA, SWITZERLAND. 



253 



maple, ten of which have already been fonnd with fruit. Although 

 in no one region of the globe do so many maples now nourish, we 

 need not suspect Professor Heer of having made too many species in 

 this genus when we consider the manner in which he has dealt with 

 one of them, Ace?' trilobatum, figs. 182, 183, 185. Of this plant the 

 number of marked varieties figured and named is very great, and no 

 less than three of them had been considered as distinct species by 



Fig. 183. 



Acer trilobatum. 



a. Abnormal variety of leaf. Heer, pi. 110, fig. 16. 



b. Flower and bracts, normal form. Heer, pi. Ill, fig. 21. 



c. Half a seed-vessel. Heer. pi. Ill, fig. 5. 



Fig. 185. 



Fig. 184. Acer rubrum, L. Fig. 185. Acer trilobatum. 



Living in TS. America. Fossil, (Eningen. 



Heer, pi. Ill, fig. 22 ; natural size. Heer, pi. 155, fig. 9 ; natural size* 



a. The carpels. c. Three petals of the corolla. d. Calyx. 



Fig. 186. Acer trilobatum. 

 b. The two carpels. Heer, pi. Ill, fig. IS. 



othei botanists, while six of the others might have laid claim, with 

 nearly equal propriety, to a like distinction. The common form, 



