196 ASPLENIUM PINNATIFIDUM. PINNATIFID" SPLEEN-WORT. 



draw from analogy against the original identity of parentage of 

 these two very different species ; and this consideration gives them 

 an additional interest unusual among plants, wherein grounds 

 for idendty of origin often exist without the opportunity for 

 comparison offered here. 



The name Asplcniiuu pinnatifidum is usually credited to Nut- 

 tall, who described it under this name in his " Genera" in 1818. 

 But the plant was known to Muhlenberg, the famous Pennsylva- 

 nia Botanist, Avho in 1S13 included it in his " catalogue " as Asplc- 

 niuin rhizophylhun, variety pinnatifidum ; by which we see that 

 the only relationship Nuttall has with its history is the expression 

 of his belief that it was a litde more distinct from the Walking 

 Fern than Muhlenberg thought it was. 



For a long time it was believed to be confined to the rocks of 

 which Nuttall speaks, on the Schuylkill near Philadelphia, and 

 a few places in the South. Even so late as 1870, Professor 

 Gray says in his "School Botany," that "it is very rare." But 

 it is probable that Muhlenberg, before Nuttall's time, had speci- 

 mens from near his own Lancaster home. Professor Porter has 

 found it there, as well as at Christiana, York, and other places in 

 the State of Pennsylvania. The writer of this found it abun- 

 dandy on rocks at South Pass, Illinois, in 1865 ; and Mr. William- 

 son, in the " Ferns of Kentucky," speaks of it as abundant on 

 the sandstone and limestone rocks of that State. It has been 

 singularly overlooked, and the endeavor to find it in other places 

 than those recorded, may give much zest to the fern-lover's explo- 

 rations. 



Explanations of the Plate. — i. A full-sized plant from a cleft in a rock in Fairmount 

 Park, Philadelphia, collected by Mr. Joseph Meehan. 2. An enlarged pinnule showing 

 the veins and fructification. 



