Algae. 411 



forms, and he made the littoral tlora the main object of his studies, 

 as enabling him to carry out ecological observations. Under the 

 headino- of "On the mode of Life of the Caiilerpaä'' he deals with 

 the foliowing points: 1. Do all Caiderpas grow under similar cxternal 

 conditions? 2. Difterent Ecological T\^pes as distinguished by varying 

 developments of their Root-system. A. Caulerpa verticillata type. 

 B. Sand Caiderpas. C. Rock and coral Caiderpas: a. C. laetevirens 

 tj'pe, b. the remaining rock and coral Caiderpas. 3. Different ecolo- 

 gical types as distinguished by varying developments of their 

 assimilation System, dividing this section into a. The bilateral leaf- 

 like Caiderpas. b. The radial Caiderpas and c. C. sertidarioides type. 

 4. On the difference between morphological and adaptational 

 characters in Caiderpas. The author finds that the Ceylon species of 

 Caulerpa grow, in the larger number of cases, on firm rocky or 

 coral ground; but they also occur frequently on soft ground, sand, 

 coarse gravel or even in mud carried out to sea by fresh water 

 streams. The manner in which the species are modified in form to 

 suit their surrounding is treated rather fully. C. clavifera is characterized 

 as being the coral-reef species, par preference. 



The next section of the paper is "On the different kinds of 

 Variation in Caulerpa'' and the author finds that the following may 

 occur in one and the same Caulerpa: 



1. Variations which depend on the locality, and which are to be 

 considered as adaptations or ecologisms. 



2. Variations which cannot be considered as ecologisms, but 

 which are the result of fluctuating variability amongst the different 

 branchlets {=■ pinnules). 



3. Variations which can be considered as phylogenetic stages of 

 evolution (for instance, that the basal branchlets or pinnules are of 

 more primitive form than the upper branchlets.) 



4. Bud variations of atavistic origin. 



5. Dwarf forms. 



6. The variations which do not fall under any of the above 

 categories ma^^ lastly, be but variations without atavistic origin 

 (-- mutations). 



Under "Taxonomy of the Caulerpas. Definition of the 

 Species", the author explains his views as to the limits of the species; 

 holding that a narrow view makes for clearness and that it is more 

 satisfactorj^ to emplo}" a limited than a broad species definition. This 

 line is foUowed in his subsequent treatment of the individual species, 

 of which he recognises 21 for Ceylon. He defines the following new 

 forms: C. taxifolia W. v. B., formte typica, tristichophylla and 

 iuterrupta; C. Lessoiiä Bory formae typica, tuticoriueusis; C. clavifera 

 Ag. f. reinota; C. uvifera f. planiuscida ; C. laetevirens Mont. f. 

 depauperata and f. caespitosa: C. imbricata (Kjellm.) f. minor and f. 

 niixta; C. sedoides Ag. f. mixta; and describes two new species, 

 C. dichotonia, allied to C. laetevirens and C. Lamourouxii; and C. 

 parvida approaching C ninnmidaria and C. imbricata. Certain species 

 which had fceen sunk into varieties of other species are here revived. 



The section ''On the Geographica! Distribution of the 

 Caulerpas" is divided into; 1. "The Distribution of the Cau- 

 lerpas in Ceylon" under which it is shewn that the different 

 external factors obtaining in the various parts of the island encourage 

 the occurrence of different species respectively. 2. "The Distribu- 

 tion of the Ceylon Caulerpas in other places" shews ..that 

 3 species are only known hitherto from that iskmd, while the ma- 



