182 BRITISH MARINE ALGAE. 
expands into a broad, obovate, perfectly smooth lamina or plate-like 
leaf, undivided (except by accidental laceration, or the inward force of 
growth), and beautifully rounded at the top. The ordinary place of 
growth is in shady rock pools, where frequently the fronds are beautifully 
iridescent. I have found this species on all parts of the English coasts ; at 
Plymouth, in Torbay, and on the shores of Durham and Northumberland, 
all equally fine and presenting precisely the same characters. The colour 
is a deep blood-red ; it is in perfection from early summer to the end of 
autumn, and fruits during winter. Spores are collected in immersed 
favellidia near the terminal portion of the frond; tetraspores are also 
produced in the substance of the plant just within the external cellular 
stratum. 8S. Dubyi, dedicated to M. Duby, was formerly Kallymenia 
Dubyi. Fig. 169 represents a mature frond-of this fine species; the plant 
from which our illustration was taken is one of the finest specimens I ever 
met with; it was over 14in. high. The frond is always undivided, except 
by accident or the force of the waves, but the margin is sometimes waved 
or curled, though otherwise perfectly smooth and entire. The rootisa 
small dise, and the base of the leafy frond is wedge-shaped, the tip being 
usually rounded. It is a summer annual, and is met with in fine condition 
in the Falmouth Harbour, in the sheltered bays near Plymouth, and in the 
west of Ireland. This species I have never found growing in tufts, the 
frond is always, I believe, solitary, even when several specimens are met 
witk growing near each other in the same locality. The colour is a 
brownish red ; favellidia of small size are scattered abundantly over the 
surface of the plant. 
The genus Catenella contains a few species of very tiny plants, one of 
them only being found in Britain, known as Catenella opuntia. Fig.170 a, 
represents a plant of the natural size, and b, some of its little branched 
filaments highly magnified. The fronds are scarcely more than lin. high ; 
they arise from creeping fibrous roots, and are densely interwoven, every 
portion of the plant being composed of little strings or chains of elliptical 
joints, whence the name, which is from the Latin for a little chain. This 
diminutive plant is generally considered rare, but its small size doubtless 
causes it to be frequently overlooked. I have, however, found it once 
only in the south of England; but I have received it from collectors near 
Filey, who obtain it there often very abundantly. The spores are contained 
in capsules attached to the upper articulations of the frond, tetraspores 
are immersed in the ramuli; the colour is a dull purple, turning blackish 
in drying. 
Gloiosiphonia capillaris, represented by a few branches at a, Fig. 171, 
is one of the rarest and most beautiful of the British red filiform alge. 
This plant is very difficult to display nicely on paper; the stem and 
principal branches are tubular, but soft and gelatinous, as expressed 
in the generic name; the branchlets and ramuli, although capillary 
or hair-like, are so juicy and flaccid that in drying they press upon 
each other and clot together, so that it is extremely difficult to make a 
