IHE CEYLON SPECIES OF CAULERPA. 



125 



root-branches fixed to the scarred rocks ; on the other hand, the vertical axes are few and with ratiier large 

 intervals between them. The result is that the plant becomes firmly fixed, because the rhizome and the 

 system of roots are so strongly developed in comparison with the relatively few and short assimilation 

 branches which they have to keep attached. The vertical axes are slender with close pinnules. These, 

 in regard to their form, may vary a httle, in that they are sometimes quite cylindrical — which is 

 the most common, sometimes more clavate and somewhat flattened laterally. The former kind 

 of branches is the commoner, and if both kinds occur on the same vertical axis the cylindrical 

 ones are to be found at the base, the clavate ones at the top. This form is precisely Grevillb's C. Ictica 

 (H/iRVEY , Ceylon Algae No. 64) according to specimens in J. G. Agardh's Herbarium in Lund (No. 6,744). 



Fig. 19. — C. IcBtevirens (mont.) /. Inxa (grev.); (a — i 1 x 1 ; k 2 x 1). 



As specially characteristic of forma laxa and what may also be regarded as a kind of adaptation 



to its manner of growth in strongly exposed places, is its very strongly developed formation of rhizomes : 



see fig. 19. In this connection it may be especially pointed out that this form shows great inclination 



to let the branchlets grow out to horizontal axes which take root and contribute to attach the plant ; 



