294, BRITISH MARINE ALGA. 
Harvey. C. arbuscula I have taken in Scotland only ; C. granulatum 
I have found in Torbay, and at Plymouth frequently, but on no northern 
shore. The branches of this shrub-like plant are very closely set, but 
are spread out in all directions ; and these throw out a second and third 
series of lesser branches, all of which terminate in little fan-shaped 
branched ramuli, the tips of which are forked, the outline being somewhat 
arched. Tetraspores are produced singly, in or near the base of the forked 
ramuli; as seen in the magnified branchlet at c, Fig. 202, bilobed-favelle 
are placed in the angles of the branches. The colour is a purplish red ; 
but allmy specimens in drying became a most beautiful sepia, or sometimes 
Vandyke brown. C.corymboswmis one of the rarities, as well as one of the 
most delicate of this genus; its general appearance is represented at 
Fig. 208. Callithamnion corymbosum. 
Wig. 203. The terminal branchlets are fastigiate or level-topped at the tips, 
which are of the utmost tenuity, and are crowded together to such an 
extent, as to appear like numbers of little red corymbs crowning the 
branches, whence the specific name. The branching of this species is 
often very irregular, but the great length of the joints in the stem 
and branches, and the bifid tips of its corymbose terminal branchlets, are 
characters so distinct that it cannot very easily be mistaken for any 
_other species. ‘The tetraspores are attached to the sides of the joints just 
below the forkings of the terminal ramuli, as represented at a, Fig. 204, and 
the favelle, which are bi-lobed and of large size, are produced in the axils 
of the branchlets, immediately under the little rosy-red corymbs, as seen 
at b, Fig. 204. The substance is so soft and gelatinous that the plant 
adheres perfectly to paper when drying. A most lovely, and, as it appears 
