126 



CEYLON MARINE BIOLOGICAL REPORTS. 



they are consequently a kind of haptera (fig. 19 a, c, f, g, h, i) ; but these branchlets again form vertical 

 axes and behave exactly as the other horizontal axes. The figures show several examples of this : so in 

 fig. 19 /.we see a vertical axis where most of the pinnules at the base are gone, and only a few remain, 

 which are just in the stage of growing out. They have not, however, as yet reached any length. Different 

 is the case, on the other hand, with those which are given in fig. 19 a, g, h. In fig. 19 a, for instance, 

 may be seen a fully grown branch beginning to branch; in fig. 19 h, where, moreover, several branchlets 

 have grown out it has formed roots too; and the same is the case in fig. 19 i, &c. In aU these cases it 

 has been assimilation branches that have changed character and turned into attaching organs. These 

 changed branchlets might possibly be looked upon as of Uttle value, since they do not develop in the 

 same level as the rest of the rhizome system ; but here we must observe that the rocks are, of course, very 

 uneven, with crevices and cavities, so that the haptera easily grip, even if they are developed higher 

 up. This form with its creeping and chmbing rhizomes entangled in each other forms almost 

 mat-like associations, from which here and there rich shoot systems radiate. Of aU the Caulerpas 

 I have studied in Ceylon there is none which shows itself in its system of shoots so well adapted for the 

 conditions of life in which it grows as this. That the same seems to be the case with this species in other 

 places, for instance Western Austra'ia, can be gathered from Harvey's notes ("Phyc. Austr." I., PI. 30). 

 Habvey says that the rhizomes form mats of the length of an inch or more with numerous and long roots, 

 an apperance which is also to be seen in his figures of this plant. Harvey also mentions that it grows 

 " in exposed tide-pools " even if it is not absent in sheltered places. 



But the branchlets Tiot only grow out into new rhizomes, but may also directly branch and form 

 new assimilation branches. This is also a rather common case and several examples of it are to be seen 

 in fig. 19 a, d, e, h, i, k. In fig. 1 9 f/ appears an assimilator where three to four closely set branchlets have 

 grown out in this manner into new assimilators, which are placed as a whorl around the main axis. In 

 fig. 19 A; is shown, doubly magnified, a young assimUator of which the branchlets have begun to part them- 

 selves in several branchlets. In few Caulerpas can the branchlets change so easily both into rhizomes 

 and into new assimilators as in Icetevirens f. laxa. The branchlets thereby very evidently betray their 

 shoot-nature. 



I have never seem any forms so big that they could be classed under 

 /. typica, Webber v. Bosse {loc. cit. p. 366), nor have I seen any that 

 could be classed under /. cylindrica with any certainty ; practically all are 

 identical with /. laxa, Grev. But, on the other hand, one can sometimes 

 find forms as exceedingly stunted as those figured in fig. 20 and which I 

 have called /. depawperata. Such dwarf forms may also be seen in other 

 Ceylon Caulerpas. 



Fig.'20. — C. Icetevirens (mont.) 

 f.depauperatan. f. (1 x 1). 



Fig. 21. — C. Icelevine^is (MONT.) 

 f. caeapitosa n. f. (\ x 1). 



Fig. 22. — C. ketemretis (mont.) /. ccespUosa n. f. 

 (2 X 1). 



As an ecological foi-in of great interest /. ccespitosa (figs. 21, 22) is worth considering. It 

 differs partly by being somewhat smaller and in Ihu form and rigidity of its branches, and partly and 



