ALGÆ ANTARCTICA, 261 
or slightly compressed, tufted, rising from a mass of creeping 
fibres. Colour dull purplish, similar to that of G. purpuras- 
cens. 'lhis may possibly be Agardh's Spherococcus subulatus 
B nigrescens, a point which cannot be determined without 
comparison with his specimens. 
25. Gracilaria? aggregata, nobis ; cæspitosa, nigrescens, è basi 
communi late scutata carnosa orta, frondibus filiformibus 
subcompressis cartilagineis vagé ramosis subdichotomis, 
axillis angustis, ramis erectis simplicibus vel furcatis om- 
nibus filiformibus obtusis, apicibus subfastigiatis, fruc- 
mr... 
Has. Falkland Islands. 
Frond 3-4 inches high, scarcely half a line in diameter, 
springing in dense tufts from a common fleshy scutate base, 
which is nearly an inch broad, irregularly branched; some- 
times the lower half is simple, the upper part of the frond 
only being branched ; sometimes it is nearly regularly dicho- 
tomous. The axils are obtuse, and all the divisions remark- 
ably erect. The colour is blackish purple; the substance 
cartilaginous ; and in drying it scarcely adheres to paper. 
The habit of this species has some resemblance to that of 
Polyides rotundus. 
ACANTHOCOCCUS, Nov. Gen. 
Frons linearis, compressa, distiche ramosa, cartilagineo- 
carnosa, rosea. Axis solidus, densus, e cellulis minutissi- 
mis formatus, tubulis magnis pluriseriatis extus sensim 
minoribus circumdatus.  Peripheria cellulosa, cellulis 
parvis reticulata. Coccidia globosa, aculeata, in apicibus 
ramulorum immersa, sporis numerosissimis repleta. 
26. Acanthococcus Antarcticus, nobis. 
Has. Cape Horn and the Falkland Islands. 
Frons 4-8 uncias alta, compressa, anguste linearis, basi semi- 
lineam vix ad lineam latitudine, sursum sensim angustata, 
distiche ramosissima. Rami patentes vel divaricati, nunc 
flabellatim multifidi, nunc pinnati et bipinnati ; secundarii 
nunc breves subsimplices, nunc longissimi, ramosissimi. 
