The following preliminary communications about some new 

 species or forms of calcareous algæ from different tracts as well 

 as a few formerly described but hitherto not well known species 

 will on a subsequent occasion be foUowed by a number of pictures. 



L i t o t h a m n i o n b r a c h y c 1 a d u m Fosl. mscr. 



Thallus forming roundish balls of radiating short, 3 — 6 mm. 

 thick branches which are knotty and riigged, more or less anasto- 

 mosing and fastigiate, otten with thickened ends. Conceptacles of 

 sporangia seen from above 500 — 700 ji in diameter, slightly pro- 

 minent and a little flattened in the central parts. Sporangia four- 

 parted, 180—220 jj. long and 70-80 /^ broad. 



The present species bears a striking likeness to coarse speci- 

 mens of Lithophyllum racemus f. crassa. I have seen but a solitary 

 specimen furnished with conceptacles of sporangia in the collection 

 of British Museum. It is probably the same specimen referred by 

 Prof. Dickie^) to Lithophyllum racemus, and not unlikely also 

 the species mentioned by Melliss^) under the same name. 



The conceptacles of sporangia are partly scattered partly rather 

 densely crovvded in the upper part of the branches, slightly pro- 

 minent and as a rule a little tlattened in the central parts, here 

 traversed by about 40 delicate muciferous canals. The sporangia 

 are four-parted, 180 — 220/^- long and 70—80/^ broad. The con- 

 ceptacles at length grow down into the frond. 



In structure it does not show any regular development. On 

 a longitudinal section of a branch is to be seen indistinctly cup- 



1) G. Dickie, The Marine Algæ of the Island of St. Helena. Linn. Soc. 

 Jouni. Bot. Vol. 13. Pag. 179. 



2) J. C. Mel lis. St. Helena: A Physical, Historical, and Topographical de- 

 scription of the Island, including its Geology, Fauna, Flora, and Meteorology. 

 London 1875. Pag. 382, No. 1052. 



