36 
lar in all respects to European specimens of 1. lacustris collected 
by Durieu de Maisonneuve. The plants at this station are but 
few, being interspersed among those of P. echinospora Braunii and 
are perhaps from spores brought down the river by the current. 
This species may be expected to occur more abundantly in the 
northern portions of Now Hampshire and Maine. 
I. lacustris is reported in Bishop’s Catalogue of the Plants of 
Connecticut (1896) as having been found at North Stonington, but 
an examination of a much larger number of specimens from this 
locality has shown that they should be referred to I. Tuckermani. 
I. lacutris is abundant in the lakes of northern and central 
Europe. 
Illustrated in Gray s Manual, and spores and leaf sections by 
Motelay. Early in August. 
232. I. Tuckermani A. Braun. Leaves dark olive, often 
tinged with red, very slender and fragile ; outermost recurved 
spreading, usually sub-distichous and spirally twisted, 2 -5 inches 
long ; peripheral bast-bundles absent ; stomata few or none ; spo- 
rangia small, orbicular, rarely pale spotted ; velum one-third indu- 
siate ; macrospores 450-750 // in diameter, marked on the upper 
half with parallel or often anastomosing ridges, the lower hal- 
irregularly reticulated ; microspores 25-38// long, dark gray, near- 
ly or quite smooth. 
Usually gregarious, growing in gravelly soil immersed in from 
one to four feet of water. Type locality, Mystic river, Prof. Tuck- 
erman; and in Mystic, Spy and Horn ponds near Boston, Mass., 
W. Boot. Abundant on the east side of Chebacco pond, Essex, 
Mass , and at Lake Atitash, Amesbury, Mass , growing in compa- 
ny with I. echinospora Braunii, which however is always found 
nearer the shore and often wholly emerged. This species is 
plentiful also on the muddy shores of the Merrimac river at New- 
buryport, Mass., growing in places subject to a tide of two or three 
feet. Fifteen or twenty per cent, of the plants at Lake Atitash 
are trilobed 
