62 BRITISH MARINE ALGR. 
which grew in one of the tide pools in Torbay, where it is usually very 
abundant. The root is a very minute disk; the fronds are from 3in. to 
Sin: or 10in. high, and when fully grown are somewhat more than 2in. 
in width. They are generally oblong, with broadly rounded tips, and are 
tapered suddenly at the base; the margin is generally flat, but sometimes 
waved or curled; the colour is a pale olive green, turning to a lighter tint 
of green in drying ; though occasionally, if mounted fresh from the sea, this 
species preserves its natural pale olive tint. The spores are produced on 
both surfaces of the frond, and, under the microscope, are found to be par- 
tially concealed amongst tufts of little club-headed filaments. Fig. 66 
represents two well-grown fronds of P. plantaginea, the plaintain-leaved 
punctaria. This species grows in tufts in rock pools between tide- 
marks. The fronds are from 3in. to 10in. long, but are much narrower than 
those of P. latifolia, the widest part being near the blunt or rounded 
tips, from which.they gradually taper to the base, the root being a very 
small naked disk... The substance of this plant is thick and tough, and 
of a dark brown coiour, a character which it retains in drying. It is rarely 
curled at the margin, the long narrow leafy fronds giving it some- 
what the appearance.of young plants of Laminaria fascia (Fig. 45), from 
which it may, however, be always. distinguished by the fructification, 
which is usually abundantly present. scattered in spotlike groups over 
both surfaces of the fronds. It is a summer annual, and is found pretty 
generally all round the British coasts. P. tenwissima (Fig. 67, a) is the rarity 
of its tribe. I took asingle specimen of it many years ago at Brighton, but 
have never found it since. Itis said to be parasitic on Zostera marina 
the common grass-wrack, which is so abundant on sandy shores; but 
although I have examined thousands of specimens of this marine plant in 
various parts of Scotland, and all round the shores of England, I have 
never been rewarded witha single plant of P. tenuissima. Of course, I 
cannot presume to say that botanists are wrong in mentioning the 
fronds of Zostera as its parasitic habitat; I can only say I never found 
it growing on that plant, but I have found it on Chorda filum (Fig. 49), as 
represented by a portion of both in Fig. 67, a. The fronds, which grow 
in clusters all round the slimy sea-chord, are from 3in. to about 10in. 
long, and are about jin., or rarely more than fin. wide, gradually 
narrowing towards the tips and much attenuated towards the base, of a 
delicate and almost transparent substance, and of a pale olive colour, turn- 
ing to a bright green in drying. No fruit has hitherto been detected on 
this species, and as my plants are all barren, [ am unable to describe 
the fructification of this rare alga. The late Mrs. Griffiths, of Torquay, 
is said to have considered it asthe young of P. latifolia, and perhaps 
the absence or rarity of fruit on this species may have led to such a con- 
clusion. I, however, do not share that opinion. The only specimens 
of this plant ever found by me were growing in widely different situa- 
tions to any in which I ever met with P. latifolia, and in all the 
numerous rock pools in which I have watched the growth and development 
