75 



in sections can now and then be found conceptacles or parts of such ones which are over- 

 grown. The plant bears sporangia in 

 the months of February, June and July. 



This species is apt to be over- 

 grown by other calcareous algae and, 

 therefore, it is more frequently found 

 covered than uncovered. It is, however, 

 easily recognizable even in a sterile 

 stage. In habit it partly recalls certain 

 forms of Meloèesia, partly crustlike 

 Lithothamnia, sometimes rather appro- 

 aching to e. g. young specimens of L. 

 simulans, though this species is forming 

 more even crusts. Besicles, fertile spe- 

 cimens recall crustlike forms of Gonio- 

 litkon, to which genus the plant is 

 nearly related. Otherwise it comes 

 nearest to Mastophora pacifica, but the 

 latter species shows mostly longer cells 

 and also differs in other respects. 



Occurrence: The species is 

 commonly distributed over the greater 

 part of the investigated area, but is 

 on the whole scarce. It seems to occur 

 not only in shallow water, as is probably 

 the case with most of the other species 

 of this genus, but it descends to a 

 rather great depth. In most cases, 



however, it has only been found overgrown particularly by other calcareous algae. Cp. the list 

 of stations with the particulars aclded. 



Area: Indic: The Maldives and Laccadives M, the Red Sea 1 ). 



Fig. 31. Mastophora mclobesioides Fosl. 



A. Part of a vertical section of the type specimen; 



B. Similar section of the specimen fig. 30 C; X 72. 



I have above under Lithothamnion fragilissimum mentioned some calcareous algae 

 occurring in fossil sediments from Xew Guinea, among them also Mastophora mclobesioides. 



It has generally been assumed that recent Lithothamnia also are represented in fossil 

 sediments, i. e. the genera Lithothamnion and Lithophyllum at least. But a comparison between 

 fossil and recent species has seldom been made, particularly because ol the unsufficient know- 

 ledo-e of these algae. An exception forms however Lithophxllmn racemus, a species which 



1) At the Laccadives it has been found overgrown by Goniolithon laccadivicum, and at El Tor in the Red Sea overgrown by 

 Goniolithon Fosliei. 



