208 MR. б. MURRAY ON NEW SPECIES OF CAULERPA. 
define, I have always taken a favourable view, strengthened by observation of several 
species in the living state and their mode and habit of growth. I now propose to 
submit reasons, of a modest character certainly, but yet I trust of some weight, for 
believing that such an affinity exists. 
A few weeks ago Mr. E. M. Holmes brought to me a form of Caulerpa which he 
believed on good grounds to be undescribed. Не very kindly handed it over to me for 
description, and I have much pleasure in now formally making it known under his 
name as follows :— 
CAULERPA HOLMESIANA, n. sp. (Plate LII. figs. 1 & 2); frondibus a surculo repente 
annulatim constricto erectis, irregulariter ramosis, annulatim constrictis, rhachide 
rugulosa inferne nuda superne pinnata, pinnis oppositis eximie patentibus, faleato 
incurvis, in apiculum evidenter productis. | ! 
Hab. ad Algoa Bay, Becker ! 
In its branching and in the form of the pinne, even to the apieulate ends, this species 
very closely resembles C. plumaris, Ag., from which, on the other hand, it differs wholly 
in the character of the sureulus and branches themselves. In C. plumaris and its allies 
these are terete and regular—in C. Holmesiana both surculus and branches are, as- may 
be seen from fig. 15, annulate and rugose. This annulate structure is characteristic of 
С. cactoides, Ag., and of the base of the fronds of С. ligulata, Нагу. (fig. 3, а & 0). 
Viewed in section the stalks exhibit the lattice-work of cross-beams or strands of cell- 
membrane characteristic of Caulerpa (Plate LII. figs. 2 а & b, 3 b, Та & b, Plate LIII. 
figs. 2, 5, & 6), but except in this respect they call to mind very forcibly the outward 
appearance and structure of the basal cells of the Valoniacee named above, viz. Struvea, 
Chamedoris, and Apjohnia. А reference to fig. 4 (Plate LIT.), which represents the basal 
cell of Struvea plumosa, shows this point—not only the strong outward resemblance, but the 
peculiar character of the thickening of the cell-wall—a structure previously described by 
Mr. Boodle and myself (* Annals of Botany,’ vol. ii. p. 169) as fibrillar thickening. This 
process of thickening, which is carried so far in Spongocladia as to obliterate the lumen 
in some cases, is more or less characteristic of all Caulerpe (see Plate LII. fig. 2, 
Plate ІШІП. fig. 5), and taken into account with the vesicular character of the fronds of 
many Caulerpe, especially as they appear in the living state, it affords me grounds for 
thinking that we may have here an indication of the affinities of the genus. Тһе use 
of such annulate constrictions accompanied by thickening of the wall is plainly the 
mechanical one of strengthening the stalk. It is found, as has been said, in С. cactoides 
(fig. 6), which has a large and comparatively heavy frond; in C. ligulata (fig. 3), of which 
this is even more true; in Struvea, Chamedoris, and Apjohnia, in each of which a 
single slender stalk supports an unwieldy frond. I admit that this point is a small one, 
but in the total absence of other indications it has appeared to me to be of sufficient moment 
to claim attention. The question cannot be wholly settled until the reproduction of 
Caulerpa has been discovered, and meantime we must be content with vegetative characters. 
If a connection with Valoniacee be admitted, I may be pardoned for pointing out the 
