80 



less numbers. We find, too, that we have lost many of the grandest 

 elements in the Tertiary flora ; for example, our sycamores {Plata- 

 nus occidentalism dcadi P. racemosus^) were in Tertiary times represented 

 by a half dozen species which are now extinct, and of these, two at 

 least would seem to have surpassed in magnitude and beauty our com- 

 mon one, great and grand as it is; for I have leaves of two extinct 

 sycamores that are each one and a half feet in diameter. Camphor 

 trees, palms, and figs were also features in our Tertiary flora which 

 exist no longer outside of the tropics. 



The most potent influence which operated to change the flora of 

 the Tertiary to that of the present day was undoubtedly the cold of 

 the Ice period. Although less destructive here than in Europe, because 

 the southern extension of our continent offered a place of retreat be- 

 fore the advancing ice-sheet, the substitution of an Arctic climate for 

 the mild temperature which prevailed in Tertiary times throughout 

 the northern portion of the continent, and the spread of unbroken 

 fields of snow and ice over all the surface north of the fortieth par- 

 allel, caused the destruction of all plant life over three-fourths of the 

 area covered with the luxuriant growth of the Tertiary vegetation. 

 It also forced the remnant into such narrow quarters that vast num- 

 bers of species were exterminated, and left the flora in the fragmen- 

 tary condition it now exhibits. The effect upon the fauna was still 

 more disastrous, for a forest tree needs no greater space than is occu- 

 pied by its roots in the earth and its branches in the air, while the 

 surface required for the support of one of the larger mammals is 

 much greater. Hence of the grand Tertiary fauna scarce a remnant 

 survived, while of the plants, when better days returned, and the snow 

 fields and ice-sheets retreated to Greenland, a sufficient number came 

 back from their banishment to cover the central portion of the con- 

 tinent with a flora which retained all the essential botanical charac- 

 ters of that of the Tertiary, but the vicissitudes through which it had 

 passed had told sadly upon it. Many of its grandest and most beau- 

 tiful elements had disappeared forever, while a few of its magnolias, 

 tulip trees, sequoias and liquidambars survive as solitary representa- 

 tives of the groups to which they once belonged, and form groves 

 instead of boundless forests. Overtopping in their grandeur, or out- 

 shining in their beauty, their present associates, they attest the' general 

 magnificence of those ancient forests that were composed of their 

 progenitors and extinct relatives, their equal or superiors. 



58. Adiantum Capillus-Veneris, L., in Kentucky.-On the 28th 



of last month I received the following letter from Mr. Linney, con- 

 taining a small piece of this fern. 



■ 



Harrodsburg, Ky 

 Dear W.— Mr. E. H. Gaither of this place found last week under 

 a cascade, \ mile from Burnside's Point, Pulaski Co., great quantities 

 of A. Capillus- Veneris, if that is this form. Yours, 



T . . . AT T • y^\u. LlNNEY." 



I at once wrote to Mr. Linney to send me the best specimen he 

 could get from Mr. Gaither, and to give me all the particulars about the 

 locality. He sent me four very good plants, two of them measuring 



