36 FERNS AND THEIR ALLIES 



the sterile, with round fruit-dots near the midvein 

 which mature in July. The indusium is large, 

 smooth, and persistent, fixed by a narrow sinus, 

 the sides of which often overlap, thus causing 

 the indusium to appear round and entire. 



PITTSFORD SHIELD FERN. 



Aspidiutn Pittsfordense (Dryopteris Pittsfordensis). 



This fern is a new species discovered by Mar- 

 garet Slosson in Pittsford, Vermont, in 1895, and 

 described by her in " Rhodora " of April, 1904. 



It was found growing by the roadside near 

 Aspidiitm marginalc and a form of Aspidinm 

 spimdosimi and is thought to be a hybrid be- 

 tween them. 



The frond is bipinnate or sometimes tri- 

 pinnate below. Pinnae mostly ovate with long 

 tapering tips ; the lowest pair much the broadest 

 and triangular in form. The pinnules are set 

 obliquely to the midrib, connected by a narrow 

 wing, and on the lower side of the secondary 

 rachis or midrib are much longer than those on 

 the upper side. They are oblong, deeply cut 

 into lobes which are irregularly spiny-toothed. 

 The veins are forked. 



The stipe is scaly, densely so at the base, be- 

 coming chaffy along the main rachis and some- 

 what so on the midribs of the pinnae. Both stipe 

 and rachis are grooved. 



