LITHOTHAMNIA. 467 



The specimen of f. compressa, pictured Plate XXV. fig. 1, does not represent the type 

 of this form, the branches being somewhat broader and more compressed in ty]jically developed 

 specimens. On the other hand the branches sometimes may be almost terete, and it seems 

 that this form in fact is the tj-jiical form of the species. So also with reference to 

 f abbreviata, the specimen, pictured Plate XXV. fig. 2, shows the transition to f. subtilis, 

 a still more delicate form, although standing nearest to the former. 



This vigorous alga appears to be an important reef-builder at several places in the 

 Indian as well as Pacific Ocean, and is known from Funafuti and Onoatoa Gilbert Island. 

 At the Maldives it seems to be abundant in certain localities, attaining a height of upwards 

 of 10 cm. The plant frequently gi-ows in company with other species, as Goniolithon frutescens, 

 G. Fosliei and Lithophi/Uam oncodes, the last crustlike species sometimes even covering the 

 lower part of L. cntspedium. It seems to occur in the lower part of the littoral and upper 

 part of the sublittoral zone, but scarcely descends deeper. The old specimens collected are 

 sterile, as is frequently the case in this group of algae, while the younger ones bear more 

 or less numerous sporangia in January. 



Locality. The Maldives : Hulule, Male atoll. 



5. L. Kaiserii Heydr. 



Lithothamnion Kaiserii Heydr. in Ber. Deutsch. Bot. Ges. 1897, p. 64. 



Lithophyllum Kaiserii Heydr. I.e. p. 412. 



f. typica. 



L. Kuiserii Heydr. I.e. 



f. subplicata Fosl. 



In Vidensl: Selsk. Skr. Aarsber. for 1900, p. 14. 



As formerly remarked, it seems doubtful to me whether this plant may be considered 

 a separate species, or in fact is only a form of Lithophyllum raeemus. I have previously 

 classed it with the latter. It has been up to the present found only in the Red Sea and 

 some places in the Indian Ocean, while tj'picallj' developed specimens of Lithophyllum raeemus 

 are only known from the Mediterranean and the Adriatic. The latter plant is somewhat 

 varying, and several forms from other regions are recorded which as to habit cannot possibly, 

 or only with difficulty, be separated from it. This at least in part also applies to i. Kaiserii, 

 which sometimes almost fully resembles certain forms of L. raeemus, sometimes rather differs. 

 With reference to structure, the cells on a longitudinal section of a branch often are a little 

 longer and more naiTow. But not even in this respect is any true limit to be drawn, as also 

 L. raeemus often shows at least in part the same structure. However, I consider the species 

 in question a separate one, until it as well as other nearly allied species may have been 

 more fully examined in a larger amount of material from different localities. Among these 

 species are especially Lithophyllum Okamurai Fosl. (including L. cephaloides Heydr.), L. pallescens 

 Fosl. and L. fasciculatum (Lam.) Fosl. 



At the Maldives L. Kaiserii seems to be rather abundant, partly appearing in its typical 

 form, partly rather differing. An almost typical specimen is pictured in Plate XXIV. fig. 7. 

 Sometimes the plant becomes coarser and less densely branched, as the specimen represented 

 in PI. XXIV. fig. 5. Sometimes it more or less agrees with i. subplicata. A coarse specimen 

 of the latter form with rather broad branches is represented in PI. XXIV. fig. 6. This form 



G. 60 



