196 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 



forma obtusilobata (Schkuhr) Gilbert. — Washington (C. S. 

 Lewis); Lenox; New Marlboro. 



PELLAEA. Cmrp Brake. 



P. atropurpurea (L.) Link. Purple Cliff Beake. — Limestone 

 ledges; occasional. 



POLYPODIUM. Polypody. 



P. vulgare L. Common Polypody. — Shaded rocks, chiefly on 

 schist, but occasionally on limestone; common. 



forma attenuatum (Milde) Gilbert. — Rich woods; occasional. 

 Becket (C. S. Lewis); South Mountain, Pittsfield; Bash Bish Falls, 

 Mt. Washington. 



forma auritum (Willd.), comb. nov. — (P. vulgare P auritum Willd. 

 Sp. PI. 5: 173, 1810.) 



Becket (C. S. Lewis). 



POLYSTICHUM. 



P. acrostichoides (Miehx.) Schott. Christmas Fern. — Rocky 

 woods ; common. A plant from Lee has the frond subdivided at the 

 tip, so that there are four separate tips, the two longest 10 cm. in length. 



forma incisum (Gray) Gilbert. — (var. Schweinitzii Man. ed. 7 

 and 111. Fl. ed. 2; vid. Rhodora, 11: 35, 1909.) 



Occasional with the type. Williamstown; Florida; Washington 

 and Becket (C. S. Lewis); Lenox; Stockbridge; Great Barrington. 

 A plant collected by Walters in Lanesboro has broad obtuse and in- 

 cised pinnae of the year, while the fronds of the year before are normal. 



P. Braunii (Spanner) Fee. — On the margins of cold mountain 

 brooks, on Greylock and on Fife Brook, Florida. Two plants in rich 

 leaf mould. South Mountain, Pittsfield (S. W. Bailey). These are the 

 only known stations for this northern fern in Massachusetts. 



PTERETIS. 



{Matteuccia 111. Fl. ed. 2; Onoclea Man. ed. 7; vid. Rhodora, 21: 175, 1919.) 



P. nodulosa (Michx.) Nieuwl. Ostrich Fern. — {M. Struthiop- 

 teris 111. Fl. ed. 2; 0. Struthiopteris Man. ed. 7.) 



