112 
and separating into fragments, The Nostochinze 
comprise eight genera; they are partly marshy 
and partly marine, and include an enormous 
number of individuals ; and they are either glo- 
bular or filiform, and are suspended in a gelatine 
of definite form. The Confervoideze comprise 
thirty-one genera ; they are partly parasitical on 
rocks or barks, extensively marine, and chiefly 
marshy, lacustrine, and ditchy ; and they con- 
sist of threads or filaments, jointed either ex- 
ternally or internally, separate, and not com- 
bined in any definite form. The Ulvaceze com- 
prise six genera; their fronds are membranous, 
continuous, tubular, or flattened, but never 
ribbed or herbaceous, and very rarely purple ; 
and their fruit is a heap of sporules, either 
naked, or forming scattered and covered granules. 
The Florideze comprise eight genera; their frond 
is generally coriaceous or leather-like, and is 
either flat or filiform, unjointed, and of a pink 
or purple colour; and their spores have a pur- 
ple colour, and are either enclosed in capsules 
or clustered in sori. The Fucoideze comprise 
twelve genera; their frond is rarely mem- 
branous, generally leather-like, and always un- 
jointed, olive-green, and either flat or filiform ; 
and their spores are enclosed in capsules, which 
are either ovate and situated in a peculiar re- 
ceptacle, or pyriform and immersed in the frond. 
In his quite recent work, ‘ Algze Maris Mediter- 
ranei et Adriatici, M. Agardh divides the Algze 
into the six tribes of Ceramieze, Cryptonemez, 
Chondrieze, Rhodomelez, Sphzerococcordeze, and 
Delesseriez. 
A simpler and more comprehensive arrange- 
ment divides all the algze into the disjointed, the 
jointed, and the jointless. The disjointed algze 
occur on the stems of other plants, immersed in 
water, or floating in ponds and ditches; they 
consist of individuals which are composed of 
fragments, and have the power of selfmultipli- 
cation simply by separating or throwing asunder 
their fragmentary parts; and they are considered 
by some naturalists as aggregations of minute 
animals, and certainly lie on the organic verge 
of the animal and vegetable world. The jointed 
algze comprise many of the marine kinds and 
most of the fresh-water kinds; they always ap- 
pear to the eye like series of little green threads ; 
and they occur, in endless variety, in ditches, 
ponds, and running streams. The jointless algee 
constitute the great bulk of the tribe ; they com- 
prise all the sea-weeds, and all the broad mem- 
branaceous algze of both sea and fresh water ; and 
they consist of roundish cellules, either firmly 
adhering to one another, or connected by masses 
of transparent gelatine. Dr. Greville enumerates, 
in 1830, 575 species of inarticulated algee, whereof 
about one-fourth are British species. In his family 
Florideze are included nearly a half of our British 
algee ; but itis the Fucoidez, the Laminarieze, and 
the Ulvaceze, which give the character to our ma- 
tine vegetation. “ The former, numerous in in- 
ALGZE. 
dividuals, and very valuable, as from them kelp 
is principally made, occupy with their blackness 
all the space between low and high water-marks, 
living an amphibious sort of life, alternately ex- 
posed to the atmosphere, and covered by the tide. 
The Ulvze and Porphyree intermix with them, and 
give some variety to the shore by their green and 
purple fronds. The Laminariez occupy a lower 
zone, for they are strictly aquatic, and choose, 
therefore, a station not liable to be left dry at the 
reflux of the tide. With the exception of Z. de- 
bilis and latifolia, the others are widely and gen- 
erally distributed along our coasts, affording shade 
and shelter to myriads of creeping things, and 
becoming ultimately a source of profit to the 
agriculturist, to whom the ‘ Alga projecta wilior’ 
is an unintelligible comparison. The other fami- 
lies may be considered as subordinate; for, al- 
though many genera and species amongst them, 
as, for example, Chordaria, Furcellaria, Desma- 
restia aculeata, &c., are met with abundantly 
everywhere; and many others, though local, are 
plentiful enough, yet, from their smaller size, or 
their concealed stations, they make no material 
change on the appearance of the coast. ‘ It is 
easy to perceive,’ says Dr. Greville, ‘ that some 
species, Gelidium corneum, Phyllophora rubens, 
and Sphcrococcus coronopifolius, for example, be- 
come more plentiful and more luxuriant as we | 
travel from north to south; and, on the other 
hand, that Péilota plumosa, Rhodomela lycopo- 
diotdes, Rhodomenia sobolifera, and several others, 
occur more frequently, and in a finer state, as 
we approach the north. Odonthalia dentata and 
Rhodemia cristata are confined to the northern 
parts of Great Britain; while the Cystoseire, 
Fucus tuberculatus, Haliseris polypodioides, ho- 
domenia jubata, R. Teedii, Microcladia glandulosa, 
Rhodomela pinastroides, Laurencia tenuissima, 
Tridea reniformis, and many others, are confined 
to the southern parts. Others, again, such as 
the Fuci in general, the Laminarieze, many Deles- 
seriz, some Nitophylla, Laurentie, Gastridia, and 
Chondri, possess too extended a range to be in- 
fluenced by any change of temperature between 
the northern boundary of Scotland and the south- 
western point of England.’ The causes which in- 
fluence the distribution of the algz on a particu- 
lar coast are not well known. Temperature is 
one; but there are many facts which the admis- 
sion of this cause will not explain. ‘ A few yards 
is, in some instances, sufficient to create a change ; 
and the space of three or four miles a very strik- 
ing one; not merely in regard to species, but in 
their luxuriance and rapidity of development. 
The nature of the soil, according to Dr. Greville, 
has here much influence. ‘ Thus,’ says he, ‘ cal- 
careous rocks favour the production of some spe- 
cies, sandstone and basalt that of others; and it 
would appear that the soil has an effect even 
upon those algee which grow parasitically upon 
the stems of the larger species.’ ” 
The algee, particularly the fuci, are of very 
