NEW OR CRITICAL BRITISH MARINE ALG 377 
species has recently been found growing in company with a ——- 
of other minute alge on A. hirsutum at Alnmouth by D 
rady, F.R.S. So abundant were the parasitic plants that ‘the 
creature itself was quite masked by its deep red investment. 
34, Hatymenia tatiroria Crn. Florule du Finist. p. 142, pl. 14, 
gen. 96. Blackhead, Antrim, Ireland; Dr. Dickie. In the National 
to the structure of the frond at once akéseh to what g nus 5 ie plan 
belongs. The simple, quite undivided obovate rae patties 
this as eat at sight from Halarachnion ligulatum 
. HetmintHoctapia Hupsoni J. Ag. Sp. Aly: ii. p. 418; iii 
in the genus peppy lenses It is worthy of note that the tetra- 
sporic plants are — small and deoler: compared with those bearing 
cystocarps, and it appears to me not improbable that the tetraspores 
(of Nemalion, pt &c.) may be found on similarly dwarfed 
B50" ens 
chromatophores ; tetraspores cruciate, borne in external ¢ 
sori, accompanied by. slender, — faleate, few- scliol Senitiaees. 
Cystocarps and antheridia unkno 
36. R. Georgii, sp. unica. Fronds purplish red, 100 »-1 mm. in 
nine to clustered in dense masses, more or less confluent, smooth, 
somewhat lubricous ; ebetioat’ cells seen from above roundish poly- 
gonal, a Tose 6 » in diameter; sori 50-800 p» broad; entag 
hf —4- 
antheridia and cystocarps unknown. ‘Tab. nost. figs. 8- 
n Zostera, fringing the margins of the leaves with an almost 
etnies purplish: = border. Scilly Islands, June, 1899, and 
May, 1900; E. Geo 
I detected this fea curious and interesting alga on some leaves 
of Zostera marina sent to me from the Scilly Islands last year by 
r. George. Very few fp and those small and scattered at 
tong intervals along the margin of the Zostera leaves, were found 
last year; but in the spring of the present year Mr. George has 
found the plant in abundance, forming an almost unbroken border 
