MONOCOTYLEDONES. 73 
notes as far as they helped to elucidate this difficult 
class :— 
P. jiliformis (Nolte). From Bridge of Brodgar, Harray 
(1880). This approaches P. fasiculatus. 
P. heterophyllus. Kirbuster Loch (1875, Dr Boswell). A 
form with broad, submerged leaves. This answers to a 
Swedish specimen of P. entermedius. 
P. nitens. (Birsay, 1876, Prof. Trail.) This is a remarkable 
plant, but seems best placed under xztens. It has the stem 
much branched, with enlongated peduncles. 
P. pusillus, var. rigidus (A. Bennett) is a var. from Orkney, 
as stated in Hooker’s ‘‘ Student’s Flora,” but the locality is not 
mentioned. It is, he says, rigid, fragile ; leaves rigid, 13 to 24 
inches long, accuminate strongly, one nerved, with two fainter 
nerves in some of the leaves ; stipules long, acute ; penduncles 
1 inch long ; spike $ inch long ; fruit slightly smaller than in 
typical pusi/lus, and less keeled on the back. : 
A remarkable form of puszl/us gathered by Prof. Trail from 
the Loch of Stenness (Aug. 1876). It has much the aspect of 
P. rutilus (Wolfg.), but differs by its enlongated internodes, 
broader leaves, stipules, and fruit. 
P. rufescens and P. preelongus might occur. (I have since 
found the latter, but not the former.—M.S.) 
Genus CXCI.—ZANNICHELLIA (Linn.) 
405. Z. POLYCARPA (Nolte), Horned Pond-weed. 
Var. tenuissima (Fr.) Kirbuster Loch; mill pond, 
Swanbister. These localities are given by Dr Fortes- 
cue. G. W. Scarth and I found it in loch forming 
lower mill-dam, near Pierowall, Westray (Sept. 1909). 
Genus CXCIi.—RUPPIA (Linn.) 
406. R. sprrauis (Hartm.), Z'assel Pond-weed. Not 
common. 
Bridge of Brodgar ; Nether Biggings, Stenness; in 
bay below Standing Stones of Stenness. 
407. R. ROSTELLATA (Koch.) 
Fidge, Swanbister, 
