238 EDWARD W. BERRY 



In a general way Engelhardtia fruits are not unlike those of 

 Carpinus. There seems to be little occasion for confusion, how- 

 ever, even in poorly preserved fossil material. The fruit proper 

 is decidedly different, although this is seldom well enough pre- 

 served in fossils to be decisive. The involucre is also markedly 

 different in the two genera. Carpinus involucres are usually 

 smaller with the median wing much wider and longer than the 

 lateral wings and with somewhat different venation. 



The margins are also toothed while in Engelhardtia they are 

 always entire. I have examined fruits of all the existing species 

 of Carpinus and experience no difficulty in readily distinguishing 

 them from those of Engelhardtia, the American species of the 

 former being especially different in appearance from those of 

 Engelhardtia. I have seen involucres of the old world Carpinus 

 betulus from trees cultivated in this country in which the wings 

 had entire or nearly entire margins, but the aspect of the speci- 

 mens as a whole, because of their different proportions and vena- 

 tion, was markedly unlike Engelhardtia, and if they had been 

 found as fossils no competent paleobotanist would have been 

 at a loss regarding their botanical affinity for a single instant. 



THE GENUS PTEROCARYA 



The genus Pterocarya was described by Kunth in 1824. It is 

 made up of three or four species with very circumscribed ranges. 

 The type Pterocarya caucasica A. Meyer (P. fraxinifolia Spach.) 

 at present is confined to a limited area in Trans-Caucasus, while 

 another species occurs in northern China and one or two in Japan, 

 as shown in a greatly exaggerated way in the solid black areas 

 on figure 4. 



The determination of the fossil species from their leaves is 

 beset with difficulties but the fruits are perfectly characteristic 

 and have been found in a number of instances. 



The oldest known fossil species is recorded from the Tertiary 

 of Colorado and while the American material that can be referred 

 to this genus is not abundant at any period the genus undoubtedly 

 occurred on this continent during the later Tertiary. One record 



