Jîd. IV: 5) ANTARCTIC AND SUBANTARCTIC CORALI.INACE^K. 1 3 



the northern and much varying Lithopli. incrustans. This question, indeed, cannot 

 at present be settled with certaint)-. But at any rate Litlioph. icqnabile and L. 

 discoideiim are very nearly connected with each other. 



The species in question is distinguished from L. discoideum particularly by the 

 inconsiderable thickness of the crust, 0.5—1.? mm., decreasing towards the edge, 

 which is almost always considerably thinner than the central parts, and more or less 

 crcnulate. The surface is partly rather smooth, partly a little uneven, particularh- 

 on account of the fact that the roof of the conceptacles is often dissolved, and that 

 the filling up of the scars by new layers of tissue takes place somewhat irregularly. 

 At the same time, however, the crust shows a tendency to develop small ex- 

 crescences. This is a strong feature peculiarly in f. zcandelica, in which are finalh 

 developed a great number of small, irregular excrescences somewhat confluent, in 

 much the same way as in feebly developed specimens of L. consociatiim f. typica, 

 or even feebly plicate. In habit, this form also approaches young specimens of 

 Litlioph. falklandicum. When growing older, f. ivandelica is easily detached from 

 the substratum, most likely, however, only by being attacked by animals, and in 

 certain circumstances new layers of tissue will be developed over parts of the side 

 turning downwards of the crust. 



In describing this alga, I observed that as to structure it approaches Arc/ueo- 

 Uthothamnion, as in a section it partly shows numerous small squarish intermediate 

 cells, more or less oblique. Such cells were then known only in species of ^rc//<^ö- 

 lithothaninio7i. Afterwards, however, 1 have found that these cells parti)- occur also 

 in Litlioph. discoideum. Besides in a solitary case, I have seen similar ones in 

 Phviiiatolithoii {Clathroinorphiwi) lociilosmn from the North Pacific. In the species 

 in question, the cells mentioned now occur, now are wanting, even in one and the 

 same section. Otherwise, the structure in all essentials corresponds with L. discoi- 

 dcinii, though particularly in f. wandelica the cells are frequently a little broader 

 than they usually are in the said species. The cells of the hypothallium are 14 — 

 30 t/, rarely up to 42 ,« long, and 6 — 11 // or mostly 7 — 9 ^i broad, the length 

 being 2 — 4 times or, exceptionally, up to 6 times the breadth. The perithallic cells 

 are 9—18 u long and 7 — 9 u or up to 11 /( broad, the length being generally about 

 T/2 the breadth. Among these occur the small intermediate cells mentioned above. 



The conceptacles approach those of L. discoideum. When seen from above, 

 they are slightly depressed, 200 — 300 u in diameter. In a median-vertical section 

 they are roundish or roundish-flattened. The roof is often wholh- dissolved, but in 

 the thickest crusts overgrown conceptacles are yet found. I have seen no sporangia. 



The species is litoral on the coasts of Louis Philip Land and of South Georgia, 

 but at the South Orkneys it has been taken in a depth of 9—10 fathoms. Its 

 occurrence on the coasts of the Wandel Island is unknown to me. 



