CATALOGUE. 339 



mus, (spike 8-10' long, Reich.,) verticillis longe distantibus,") and from Reicli- 

 enbach's figure. Its habitat, moreover — "in alto maris," Sweden — renders 

 its identity with our plant improbable. On the other hand, some of the 

 broader leaved forms from our Grreat Lakes, to vs^hich the first variety above 

 closely approximates, and especially the last variety by its 3-nerved leaves, 

 seem to indicate a transition from the narrow-leaved typical form of P. pecti- 

 natus to the present plant. Found in the running brackish waters of 

 Humboldt River below Humboldt Lake; 4,000 feet altitude; August, in 

 fruit. (1,142.) 



PoTAMOGETON MAEINUS, L. Resembling P. pectinatus, but with the 

 much smaller fruit obovate-subglobose, corrugated when dry, not keeled upon 

 the broad-rounded back, crowned with a broad sessile stigma. {Koch.) — 

 Central Europe, mostly in sea-water. Var. (?) occidentalis, Robbins. 

 Stems 2P long, slender, branching, less leafy than in P. pectinatus; leaves 

 flat or canuliculate, the larger i" broad and 3' long, 1-nerved with few trans- 

 verse veins, obtuse, the smaller nearly setaceous; larger sheaths about 1' 

 long, with few nerves ; stipules white-scarious, as long as the sheaths ; pedun- 

 cles filiform, sometimes 6' long ; spikes interrupted, with about 4-6 flowers ; 

 fruit minute, roundish-obovate and with a sessile subapieal stigma, the de- 

 nuded nutlet with its keels more distinct, the sides uneven by a central ele- 

 vation partially surrounded by a shallow depression, which is margined by the 

 raised lateral keel ; embryo forming a large circle, its apex directed toward 

 its base. — Approaching P. pectinatus in habit and difiering widely from the 

 small Linnsean form of P. marinus, {P. filiformis, Nolte.) But the fruit, 

 while scarcely one-fifth as large as that of the former, is in size and form like 

 that of the latter except in its more acute keel and uneven sides. Found in 

 the fresh waters of Ruby Lake, Nevada, with P. nutans and P. gramineus ; 

 6,000 feet altitude; August, in fruit. (1,143.) Specimens with immature 

 fruit collected in the Uintas, near the head of Bear River, probably belong 

 to the same form; in fresh water at 8,000 feet altitude; August. (1,144.) 



Also very early specimens collected with P. perfoliatus in fresh water in 

 the Truckee Pass, Nevada, may belong here rather than with P. pectinatus, 

 though with thickish spikes ; 4,000 feet altitude ; July. About 3° long, 

 with longer leaves sometimes 9' in length, and with marginal nerves, on close 

 long (1-2') sheaths, and with shorter (2') peduncles, and spikes of 8-10 

 flowers. (1,145.) A very attenuated delicate form, not yet in flower, col- 



