THE FERX BULLETIN 



115 



Selaginella apus (L.). Recorded from Gibson, Jef- 

 ferson and Tippecanoe (Coulter), Kosciusko 

 (Clark) and Marshall {Scovcll and Clark). 

 New Albany, Ind. 



EXPLANATION OF MAP. 



***** — Southern limit of drift. 



i. 



Hudson River limestone and shales. 



2. 



Niagara shales and limestone. 



3. 



Lower Helderberg and waterlime. 



4. 



. Corniferous limestone. 



5. 



New Albany black shale. 



6. 



Knobstone. 



7. 



Mississippian limestone. 



8. 



Mansfield sandstone. 



0. 



Pennsylvania!! (shale and sandstone) 



RARE FORMS OF FERN WORTS— XX. 



THE FORMS OF EBONY SPLEENWORT. 



The occurrence of forking and cut-leaved forms may 

 be predicated in almost any species of fern ; indeed, con- 

 sidering the venation, the very framework upon which 

 the green tissue is laid down, the wonder is, not that 

 such forms occur, but that they do not appear more fre- 

 quently. It is a general tendencv in all vegetation to 

 be more deeply lobed and dissected when plenty of food 

 is present, and when particularly luxuriant specimens 

 are encountered, these forms may be expected. On the 

 other hand, a lack of food may produce other aberrant 

 forms of fronds, but here the variations run'in different 

 directions. 



The variations in the cutting of the ebony fern 

 (Asplenium ebeneum) are more than usually pleasing, 

 due perhaps to the clear cut outline of typical fronds. 



