60 BRIFISH MARINE ALGAS. 
where but in Lamlash Bay, in the Isle of Arran. Professor Harvey 
considers it to be merely a deep-water form of Stilophora rhizodes, and 
perhaps, indeed, it is nothing more; but, like other Melanosperms in 
similar situations, its growth and general appearance differ from the 
typical form of the genus in having fronds of much greater length, the 
axils or angles of the branchese being more rounded, the tips of the 
branchlets much more attenuated and pointed, and last and most impor- 
tant of all as regards specific distinction, the spores are seated on 
branched filaments, as seen at e, Fig. 62, and not at the bases of simple 
filaments, as in S. rhizodes. The colour is a pale olive-brown turning 
to a light greenish olive in drying. The genus Dictyosiphon contains 
cnly one British species, D. feniculaceus. The generic name signifies 
a reticulated siphon—the surface of the stem and branches of the 
plant being reticulated, the network-like markings being, on this 
species, exceedingly fine. i have usually found this pretty annual, 
during the early summer months, in rock pools, and sometimes growing 
on other seaweeds. The frond, which arises from a small disk-like hold- 
fast, is filiform or string-like, from 6in. to over 2ft. in length. The whole 
plant is excessively branched and bushy, and every branchlet is attennu- 
ated at its extremity to an exceedingly fine point. Fig. 63 is from a very 
well displayed specimen of this species. The fructification, which is rare, 
consists of little egg-shaped spores, which are scattered irregularly on 
various parts of the surface of the frond, but generally on the main 
stem. The plant from which our illustration was taken, grew in one of 
the sheltered bays in Plymouth Sound. It represents the early summer 
state of the species when it isin perfection. The colour is a light olive 
inclining to brown, but it turns to a pale green in drying. 
The genus Striaria also contains only one species. It is found occa- 
sionally between tide marks, though more frequently in five or six fathom 
water. The root is a little bag-like disk. The fronds, which are tufted, 
are from a few inches to about a foot high. The main stems are set 
throughout with numerous branches which are mostly opposite and are 
all more or less similarly branched, every portion being attenuated alike 
at each extremity. In addition to the ordinary reticulation of the surface, 
the frond. of this species, when in fructification, presents an extremely 
pretty appearance, every portion of the plant being marked with striz, or 
transverse lines or bands, which are placed very close to each other, and 
are composed of sori or clusters of spores, the peculiar arrangement of 
which has suggested the generic name, that of Striaria, the specific 
name of attenuata, being equally characteristic of the form of growth of 
its branches and ramuli. Striaria attenwata is well represented in Fig. 64, 
The plant was taken by me at Plymouth many years ago, and although 
very perfect in form, the pretty transverse bands of spore clusters were not 
developed upon it. The colour is a pale olive, but in drying, young plants 
turn to a beautiful shade of green, and but for the transverse markings, 
which are genorally present on mature specimens, this species might occa- 
