THK CEYLON SPECIES OF CAULERPA. )03 



characters. And now we see that this difference in adaptational character most closely corresponds with 

 the distribution of the species, so that similarly organized species have a common centre of distribution. 

 This clearly follows from what has been stated above, i.e., that especially davifera and nummularia 

 have quite another distribution than uvifera-peUata. And since the characters which separate these 

 two groups are to h^ regarded as adaptations to the external conditions within the respective distribution 

 districts, tliese closely related species, their organization and distribution, may be given as examjiles 

 of the principle (Wettstein, " Grundzuge d. geogr.-morphol. Methodo d. Pflanzensystematik," p. 30) 

 that forms or species which are adaptations to external conditions with a limited distribution also them- 

 selves have a distribution which coincides with that of the conditions in question. 



To the less common forms of Caulerpa that occur in Ceylon belong tlie following species : — 

 C. verticillata - C. corynephora 



C. scalpelliformts i C. leetemrens 



C crassifolia 

 C taxifolia 

 C. Freycinetii 

 G: Gupressoides 

 C. Lessonii 



C. dichotoma 

 C. parvula 

 C. longisHpitata 

 C. sedmdes 

 C. Fergusonii 



Of these C. verticillata nas only been observed at Galle, Colombo, and at Tuticorin in South India ; 

 at the first-named place locally but abundantly and, forming a special association. The species is not 

 noted from the east coast, nor from the islands and banks which form Adam's Bridge. It is thus 

 predominantly of a western distribution in Ceylon. 



C. scalpelliformis, which is probably a deep water form, is only known from the Gulf of Mannar 

 (Pearl banks, Paumben, Tuticorin). 



C. crassifolia and taxifolia hay^ similar distribution ; the former is the rarer and has Ipeen observed 

 from Weligama in the south to as far as the north enc^ of the Gulf of Mannar (Pearl bs^nks ajud Paumben) ; 

 the latter at several places within the same district. 



Sjpvaral species have only been observed in. solitai;'y specimens., as rarities. Of these — 



C. FreyQinettii (Jaffna) | C. corynephora (Tuticoyin) 



C. cupressoides (Paumben) i C. longistipitata (Paumben) 



C. Lessonii (Pearlbanks, Tuticorin) | C. Fergusonii (Paumben) 



have only been observed in the north from the Pearl banks, Paumben, Tuticorin, Jaffna, but are 

 absent from the south-west coast, which has, nevertheless, been the most closely investigated. 



On the other hand there are some species with very singular and isolated occurrence, which are 

 only known from the south coast, viz. : — C. Icetevirens (Galle, Weligama) ; C. dichotoma (Weligama) ; 

 C. sedoides (Dondra Head, Matara, Weligama) ;* also C. parvula is only known from some isolated 

 places (Beruwala in the south-west and Paumben in the north). 



If we examine these different species from the point of view of their organization and mode of 

 life, it is remarkable that several of the northern forms prove to be pronounced sand Caulerpas with 

 coarse, horizontal axes, and richly and finely branched roots, e.g., C. Freycinetii, cupressoides, Lessonii 

 Fergusonii, besides which crassifolia, taxifolia, and also scalpeUiformis join them. 



On the other hand it is to be noted that such species as C. Icetevirens, sedoides, and possibly dicho- 

 oma, which have only been observed in the south, are pronounced rock Caulerpas. The species that 

 have been observed especially in the north are, moreover, often deep water Caulerpas — for instance, C. 

 scalpelliformis, C. crassifolia, C. cupressoides , C Lessonii. C. Fergusonii — whereas tnose that have been 

 found only in the south are surface Caulerpas. 



* Not© that /. mixta has also been observed at Paumben ! 



