170 THE ROCK SPLEENWORTS. 
reply that though widely scattered, in no case is its habitat 
exactly like that of its supposed parents; for while the eb- 
ony spleenwort grows at the tops and bases of cliffs, and 
Camptosorus grows on the shelving sides of mossy rocks, 
Asplenium ebenoides prefers the niches under overhanging 
ledges. In addition, the processes of reproduction in 
ferns are such as to afford very small chance for hybridiza- 
tion. If, following Lowe’s successful experiments in 
crossing ferns by sectioning the prothallia and bringing 
the antheridia of one fern incontact with the archegonia 
of another, we could produce a plant like cdenoides from 
the sectioned prothallia of its supposed parents, the fact 
of its hybridity might be regarded as proven. Exper- 
iments are being made in this direction at present, but 
until we have definite results, it seems better‘to consider 
this a distinct species. 
In outline the fronds are much like those of the pin- 
natifid spleenwort, but are not easily confused owing to 
the fact that the pinnules are thinner, narrower, longer 
and pointed. The blade tapers from a broad base to a 
slender tip and is fully pinnate below and deeply pinnat- 
ifid above. There is great diversity in the shape and 
arrangement of the pinnules, however. Some are eared 
on one side,some on both, others not at all but are at- 
tached to the rachis by a broad base. The pinnz are very 
unequal in length, the longest often standing next to one 
thatismerely a short green ear. Some fronds, which 
appear to be juvenile examples, have a broad blunt apex 
and the lower portion merely toothed or lobed. In this 
feature of producing some fronds without tapering tips, 
it resembles the walking fern. The figure in Eaton’s 
“Ferns of North America” does not much resemble 
average specimens. Like the pinnatifid spleenwort, this 
