82 FERNS OF KENTUCKY. 
In many respeets this fern resembles so closely the 
other species found in Kentucky, that it may be even 
questionable whether they are really distinct. The rich 
soil of this region, together with climatic influences, may 
serve to produce a larger and stronger form in the P. 
hexagonoptera. There seems to be, however, this dis- 
tinction —the divisions of the lower pinnz in the latter 
are elongated and pinnately lobed, while in the P. poly- 
podioides they are oblong, obtuse, and entire. I have 
represented the two species as accurately as possible; 
and the attention of students is called to this similarity 
in the two forms in the hope that careful observations 
in future may settle the question beyond a doubt. 
