No. 5] NEW OR CRITICAL CALCAREOUS ALGÆ. 27 



phyllum from West India, but they are separated by essential 

 characters. 



The plant is iaiown from Onoataa Gilbert Islands, Funafuti, 

 coUected bj^ Finckh. Britisch Museum no. A. 27. 



Lithophyllum hj^perellum Fosl. mscr. 

 f. fastigiata Fosl. mscr. 

 f. heteroidea Fosl. mscr. 



Thallus in f. fastigiata forming roundish balls 2—5 cm. in 

 diameter, in general freely developed on the bottom, repeatedly but 

 irregularly branched from the centre, 'branches radiating, short, 

 0.5 — 1 mm. thick, knotty or rugged, densely crowded, fastigiate, 

 frequently with thickened ends; f. heteroidea attached to shells or 

 stones, branches more scantily divided and subfastigiate. Con- 

 ceptacles of sporangia at first convex. Sporangia four-parted, 

 about 50 IJ- long by 20 y.. 



I am not quite sure whether the above forms perhaps ought 

 to be considered specifically distinct, as the conceptacles in one of 

 them are not well developed. 



The form fastigiata grows in the same manner as Lithophyl- 

 lum racemus. It is either partly attached to small stones, from 

 which it apparently at length loosens itself, or occasionally sur- 

 rounding stones, but most often developed free on the bottom, 

 forming roundish or slightly compressed balls 2 — 5 cm. in diameter. 

 The radiating branches are nearly always much confluent, espe- 

 cially in the lower or inner parts of the ball, so that the branch- 

 systems are difficult to foUow, 0.5—1 mm. thick with roundish 

 thickened ends and particularly here knotiy or rugged, but regu- 

 larly fastigiate. Especially in old specimens and in the side that 

 probably has turned upwards, the ends often are truncate or even 

 nearly disk-shaped This is evidently due to the fact, that the 

 plant grows in places where the tides are running rather strong. 



The form heteroidea differs in habit rather much from f. fa- 

 stigiata. It is attached with a very thin crust to shells, stones 

 or other hard objects and very irregular in outline. The branches 

 agree with those in the latter, but are less divided, in young spe- 



