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 witli our plant improbable. On the other hand, some of the 
broader leaved forms from our Great Lakes, to which 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 MARTNUS, L. Resembling P. pectinatus, but with the 
much smaller fruit obovate-subglobose, corrugated when dry, not keeled upon 
the broad-rounded back, crowned wdth a broad sessile stigma. {Koch.) — 
Central Europe, mostly in sea-water. Var, (?) occidkntalis, Robbins. 
Stems long, slender, branching, less leafy than in P. pectinatus ; Iomvps 
flat or canuhculate, 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 & long ; spikes interrupted, wdth about 4-6 flowers ; 
fruit minute, roundish-obovate and with a sessile subapical 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 diflfering widely from the 
small Linna^an form of P. marinus, (P. Jiliformis, Noltc.) But the fruit, 
while scarcely one-fifth as large as that of the former, is in size and form hke 
that of the latter except in its more acute keel and uneven sides. Found in 
the fresh waters of Ruby Lake, Nevada, with P. natans and P. graynineus ; 
G,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 fresli water in 
the Truckee Pass, Nevada, may belong here ratlicr 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- 
