1917} Butters,— Studies in Ferns — Athyrium 191 
D. Longest pinnae of the fertile frond 5-12 cm. long, pinnules 4-12 mm. 
long, simple, sori mainly asplenioid; pinnules of sterile fronds oblong 
obtuse, but slightly toothed or lobed...... A. angustum {. typicum.! 
Willdenow described the pinnae as 1.5-2 inches long, the pinnules 
as 3 lines long. This is about the minimum size for a fruiting speci- 
men. All sun-forms with simple pinnules may be considered as 
belonging to the typical form. These are the forms to which the 
varietal names angustum and Michauaii have commonly been given. 
As thus limited, the typical A. angustum ranges from Maine and 
southern Quebec to Massachusetts and Pennsylvania, being more 
common northwards. It does not occur in the region about the Gulf 
of St. Lawrence. 
In the Gray Herbarium are the following specimens _ meg form: 
QueBec: North Wakefield, July 4, 1911, John Mac Herb, 
Geol. Surv. Canada no. 83900; Rividre St te. Mchvactite, Lower 
Canada, August 14, 1879, G. S. Pringle; Lower Canada, August 3, 
1880, C. G. Pringle. 
MaIne: Hartford, August 29, 1907, J. C. Parlin no, me very dry 
New Hampsurre: roadside in the sun, Retdobeh, <a 30, Rag 
E. F. Williams; North Conway, August 14, 1877, herb. of W. 
Lane; Kensington and Seabrook, many specimens collected by Ad: 
Eaton, including his numbers 90, 145, and 182; Hampton Falls, 
August 3, 1899, A. A. Eaton; Mt. Vernon, pee 1891, M. L. Stevens. 
VERMONT: without locality, 1855, herb. of D. C. Eaton; Dorset, 
1915, E. Hi one (N. E.). 
HUSETTS: in sun, Salisbury, July 23, ee yt. 
in moist peel Ipswich, Wm es; near n, C. E. and W" 
Faxon; Sharon, September, 1905, S. F. Poole no. 50. 
New York: Gouverneur, August 1900, herb. of E. C. Anthony. 
PENNSYLVANIA: Bald Eagle Valley, Blair Co., 1860, H. V. Bocking; 
Friendsville, rh 1906, M. H. Grant; Pocono Plateau, 1904, 
J. W. Harshberge 
ONTARIO: Port Colborne, July 12, 1901, John Macoun, herb. Geol. 
Surv. Canada, no. 66416 
DD. Longest pinnae of fertile frond 1-2 dm. long, pinnules 12-25 mm. 
long, pinnatifid, sori several on each of the lower segments, often 
horse-shoe shaped; pinnules of sterile fronds oblong lanceolate, 
strongly toothed or pinnatifid, somewhat acute. 
A. angustum var. elatius. 
ATHYRIUM ANGUSTUM var. elatius (Link), new comb. 
Pea a8 elatius Link, Fil. Sp. 94 (1841). 
Link describes the frond of his fern as sub-tripinnatifid, 3 feet long, 
pinnae 4-6 inches long, scarcely 1 line wide. The larger sub-forms 
1See Plate 123, figures 11 and 12. 
