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Dictyosphœria favulosa occurs in shallow water and often on 

 rather exposed coasts, growing on coral reefs where it is con- 

 stantly under the influence of the waves. Here the specimens are 

 not so very large, seldom more than 4 — 5 cms in diameter and 

 are most often sack-shaped. But, furthermore, it is found abun- 

 dantly in deep water down to a depth of about 40 meters. Here 

 in the quieter surroundings and in the moderate light it often forms 

 large flat expansions, some of the specimens reaching in diameter 

 12 cm. 



It is a very common species at the shores of the Islands. 



D. van Bosseæ nov. spec. 



Judging from the rather short diagnosis in M me Weber van 

 Bos se' s note I had at first referred my form to D. Versluysi, but 



after having seen an original specimen 

 of this species which M me Weber has 

 been so very kind as to lend me, I 

 think it is more convenient to consider 

 my plant as a different species even if 

 it shows a great likeness with M me 

 Weber's species. 



Quite in agreement with D. Versluysi 

 Pig 7 # our form is characterized by having a 



Dictyosphœria van Bosseæ massive thallus and by the presence of 

 n - S P- the needle-formed processes upon the 



Young plant. About (6 : 1). . 



inner walls of the cells. But my form 

 differs from that from the Malayan Archipelago by its much 

 smaller cells, on an average reaching only about half the size of 

 those in D. Versluysi; and while the needles in M me Weber's 

 specimens are about 150 p. long those in my form reach only a 

 length of about 70^, very seldom up to 100//. Furthermore, the 

 spines had a rather uneven surface in my specimen whereas they 

 were quite even in D. Versluysi. And judging from the specimen 

 I have found of this species the spines seem to be present here in 

 all the cells while in my West Indian form cells often occur where 

 they are quite wanting. When to these characters we add the 

 different geographical distribution, I think it justifiable to consider 

 our plant as a new species, to which I take the liberty of 



