384 



48 



in these exposed places they show themselves as complete contrasts. For, while 

 var. clavifera f. rediicta as mentioned above behaves quite passively against the 



sea, fastened motion- 

 less to the rocks and 

 admitting the waves to 

 run over it, Caulerpa 

 lœtevirens f. laxa takes 

 part in the motion of 

 the sea as its "slender 

 assimilators swing to 

 and fro in the waves" 

 (SVEDELIUS, p. 124). It 

 reminds one here as 

 SvEDELius has pointed 

 out (p. 85) of different 

 algal associations from 

 northern seas, which 

 can be designated by 

 the name used by Gran 



Fig. 27. Caulerpa racemosa (Forsk.) Weber van Bosse 

 var. clavifera (Turner) Weber van Bo.sse f.reducta n. f. "Bølgeslagsformationer" 



From the reef between the Hurricane Island and St. Thomas. (About 5:1.) "^ ° 



(wave-beaten forma- 

 tions) while f. reducta on the contrary may rather be compared with the crust-algæ 

 occurring often on the beach. 



Yet a third form of Caulerpa racemosa is found on rocks and coral-reefs, 

 namely, the form to which I have above given the name var. occidentalis 

 (Fig. 28). This variety which I 

 earlier in agreement with Reinke 

 referred to var. Chemnitzia and 

 under which name I have distri- 

 buted it in the Exsiccatæ of 

 WiTTROCK & Nordstedt, I now 

 believe on more thorough exam- 

 ination to be separated from the 

 Chemnilzia-groui) and that it 

 should be considered as a special 

 variety. I have used the name 

 of J. Agardh for it, as I think 

 it is without doubt that my form 

 is identical with the form of 

 Agardh, as Svedelius (1. c. p. 130) 

 has also maintained. J. Agardh 

 gives the following short dia- 



Fig. 28. Caulerpa racemosa (Forsk.) Weber van Bosse 



var. occidentalis (J. Ag.). From Longreef, St. Croix. Creeping 



on a piece of a Corallinace. (About 1:1.) 



