NAIADACEX. 63 
SPECIES I—-NATAS FLEXILIS. Rostk. 
Prats MCCCCXXXII. 
Caulinia flexilis, Willd. Spec. Pl. Vol. IV. p. 185. 
Fluvialis flexilis, Pers. Syn. Vol. IT. p. 530. 
Leaves ternate or opposite, spreading, pellucid, linear, entire or 
very finely and remotely serrate, those on the main stem with fascicles 
of leaves on their axils; sheaths shortly ciliate. 
In shallow water, in lakes. Discovered in Britain by Professor 
Oliver, in a lake near Roundstone, Connemara, between the Clifden 
Road and the sea, at a mile or two from the village of Roundstone, 
and found by Dr. D. Moore in a small lake less than a mile from 
Roundstone, on the way to Urrisbeg. 
Treland. Perennial. Autumn. 
A delicate plant, with fragile filiform branched stems growing entirely 
submerged. Leaves frequently ternate on the main stems, but generally 
opposite on the branches, } to 1 inch long, very delicate and pellucid, 
with short dilated sheathing bases, commonly with a few short laciniate 
ciliations on the margins; the upper part entire or with a few remote 
serratures more marked towards the apex. Flowers dicecious (?) or 
monecious (?), axillary. Fruit sessile, elliptical-ovoid, } inch long, 
pale brownish-olive, partly enclosed in the sheathing bases of the leaves, 
sometimes 2 or 8 together in the axils of the leaves of the fascicles, 
which are developed in the axils of the leaves on the main stem. 
The male plant I have not seen. Dr. Asa Gray suspects this species 
is monecious, but I can find no male flowers on my specimens, which 
were collected by Mr. T. Kirk. 
Flexible Naias. 
French, Nayade marina. German, Biegsames Nivkraut. 
EXCLUDED SPECIES. 
POTAMOGETON FLUITANS. Roth. 
This plant has been frequently recorded as a native of Britain; but 
the statements have invariably been corrected, some other species 
having been mistaken for it. Still it is very probable that it may 
be a British species. In the last edition of Professor Babington’s 
“Manual” it is stated that a plant gathered at Hounslow, in the 
Lambertian Herbarium at Kew, may be P. fluitans, but the Rev. W. 
W. Newbould informs me he led Professor Babington into an error 
about this plant. Although I have twice carefully examined all the 
