THE LINDEN OR BASSWOOD 237 



that it is nearer than the others to the place of origin of the genus, 

 or it may be clue simply to accidents of preservation or of dis- 

 covery since earher forms in other areas may not have been pre- 

 served at all or may still be awaiting discovery in the rocks. 



No Oligocene lindens are known and this must be ascribed to 

 the reasons mentioned at the close of the preceding paragraph since 

 in the succeeding Miocene times there was a great display of a 

 varity of lindens. They are found at this time from the base to the 

 top of the Miocene deposits of Europe, where plant beds of this 

 age are much more abundant than they are in either North America 

 or Asia. At least fourteen different Miocene species are known 

 and their remains include several of the characteristic and curiously 

 bracteate fruits which, when ripe, turn brown and serve the vol- 

 planing habit by which the distribution of the seeds is effected, 

 as well as a variety of leaves. 



The lindens are especially abundant and varied in the late Mio- 

 cene of southern Europe along the shores of the expanding Mediter- 

 ranean sea of that time, and in the Pyrenees, the foothills of the 

 Apennines and in the mountains of Transylvania, Styria and Bo- 

 hemia. The fruit of one of these late Miocene species found near 

 Vienna in Austria and named Tilia vindohonensis from the old 

 Roman name of Vienna is shown on the accompanying plate. 



The Miocene records in North America are scanty but the genus 

 was still represented in the Rocky Mountain region having been 

 found in deposits of this age in the Yellowstone Park and in the 

 lake basin at Florissant, Colorado, both of which localities are 

 now separated by several hundreds of miles of treeless plains 

 country from the westernmost outposts of the existing species in 

 the river valleys of eastern Kansas and Nebraska. 



The known Pliocene hndens, owing to the rarity of plant beds 

 of this age in North America, are confined to Eurasia, although 

 the genus was undoubtedly present in North America during the 

 Pliocene since it is found in the deposits of the immediately pre- 

 ceding and succeeding times. There are four PHocene forms 

 recorded from Europe where they are found in variety and abund- 

 ance in the Auvergne region of France, and in northern Italy. In 



