i to 3. abruptly pointed, sometimes obtuse. Leaves becoming 

 shortened in the upper verticils forming a long terminal stem, 

 about 700 // in diameter, with very short leaves in remote 

 verticils ; these upper leaves are fertile and commonly obtuse, 

 rarely apiculate. Fertile leaves once divided, first division 400 

 to 500 yu in diameter, with one terminal 700 //in diameter, rarely 

 two terminals. Antheridia, about 250 /< in diameter, usually 

 subtended by a very short, abtuse leaflet (see figs. 4 and 5). 

 Oogonia, single or aggregated, enveloping cells with blunt, 

 usually inflated tips, coronula evanescent ; oospore 460 /* long, 

 400 fJi broad with seven, thick and prominent ridges, membrane 

 of the oospore granulated. 



This plant was first gathered by the late Dr. Northrup and 

 his wife in Lake Tamiscouata, Canada ; but a single specimen 

 was taken, and a special collector sent to the lake two years 

 since failed to gather but few complete specimens, though he 

 secured a number of detached, fruiting, terminal stems which 

 had drifted to a lee shore. Fruit mature in August. 



Explanation of Plates. The photogravure was taken from Dr. 

 Northrup's collection, and is one-half the natural size ; in the 

 lithograph, 3, the female plant, x 25 ; 4, the male plant, x 25 ; 5, 

 tips of fertile leaves, x 25 ; 6, an oogonium, x 50 ; 7, a portion 

 of the spore-membrane highly magnified, showing the closely- 

 granular surface and a portion of a thick ridge ; 8 and 9, apicu- 

 late terminals, x 25 ; 10, an obtuse terminal, x 50 diameters. 



NITELLA MONTANA, Sp. \\ov.--Monarthrodactyla, furcata, 

 honnvophylla, dioica, gymnocarpa, acuminata. 



Plants small, from 3 to 7 cent, metre high, branched and 

 delicate ; the upper verticils fertile. Leaves 8 in a verticil, 

 once divided ; terminal divisions, 1-3, gradually acuminate. In 

 the verticils may be found additional very short leaves (shoots) 

 fertile, so short that the fruit seems almost sessile in the verticil. 

 The stems are about 600 /*. in diameter ; the first division of the 

 leaves, 350 /^., and the terminals about 200 //. in diam., tapering 

 to a sharp point. The oogonia are numerous, 1-3 together at 

 the forks of the leaves ; coronula persistent ; oospore when 

 mature, 440 //. long ; 390 to 400 //. broad, with 7 or 8 somewhat 

 blunt ridges (not so thick as the ridges on N. opaca) ; mem- 

 brane of the spore finely and evenly granular. Antheridia, 750 /^. 

 in diam., when fully developed, 



