128 



CEYLON MARNIE BIOLOGICAL REPORTS. 



24 a. In general, the branchlets at the base seem to be undivided (fig. 24), and the dichotomous branchlets 

 only begin higher up. On the other hand, assimilators from the same horizontal axis occur, with both 

 prevalently simple and prevalently dichotomous branchlets 



Fig. 24.— C. dichotoma n. sp. (2 x 1). Fig. 25.— C Lamourouxii (tttrn.) from Yemen coll. 



by MoNTAGNE- Specimen in the Herb, in the 

 R. Kiksmuseum in Stockholm. (1 X 1). 



This Caulerpa is without any doubt nearly related to both C. Icetevirens and such types as corynephora 

 or Zeyheri. The correspondence with C. Icetevirens, especially the /. laxa, shows itself in the simple 

 pinnules, especially at the base, which also in /. laxa are somewhat flattened together from the sides. 

 .Moreover, the vertical axes are often cylindrical in C. dichotoma, in which case also the pinnules radiate from 

 all sides, and this is especially the case at the base. The plant, too, at a first glance gives the impression 

 of a C. Icetevirens, though the mode of growth is rather different. On the other hand, the flattened 

 axes with their opposite pinnules indicates a close resemblance to coryn&phora. But a new fact is added 

 to this, viz., the tendency of the pinnules to branch dichotomously, and it is this character that justifies 

 the creation of this plant as a special elementary species. A certain resemblance seems to be present to 

 the little weak /. Zeyheri, too, which has also the pinnules opposite and laterally flattened ; 

 but it is always very slender, and at the same time it has always simple pinnules of somewhat diJGEerent 

 shape, so that a confusion with G. dichotoma is not likely to occur. However, C. dichotoma is very 

 similar, or at least analogous in its development to both Icetevirens and Lamourouxii (in Weber v. Bosse's 

 definition). In the Herbarium in the R. Riksrauseum in Stockholm there is a Caulerpa labelled C. clavifera 

 Ag. (Yemen) from Montagne's Herbarium. On the same shelf are mounted two distinct forms, not only 

 tjrpical clavifera, but also some specimens of another with fiat axes and opposite sparse pinnules with the 

 appearance of G. Lamourouxii (PI. XXXII. I Weber v. Bosse, lac. cit.). On one of these (fig. 25) there are a 

 few axes in which some branches show a trace of this very dichotomy which occurs typically in C. dich- 

 otoma. And on a closer examination of other Caulerpas I also found in the Herbarium in the Copenhagen 

 Museum a Caulerpa on the label of which was only noted that it had been collected in " India orientalis." 

 with similar dichotomous branchlets. It is a rather low, flat Caulerpa with sparse single branchlets. One 

 of these is dichotomous. But in none of these latter specimens were the dichotomous branchlets so 

 plentiful as in dichotoma. Probably G. dichotoma is a form which is closely allied to Icetevirens and Lamour- 

 ouxii, which two latter are themselves closely allied. But this does not prevent dichotoma being distin- 

 guished as a special elementary species, and Reinke is undoul>tedly right in pointing out that the 



