Bil. IV: 5) ANTAKCTIC AND SUBANTAKCTIC CÜRALI.INACE.E. 



7. Lithothamnion heterocladum Fosl. 



Vidensk. Selsk. Aarsher. (Bot. Sarnl.) 1904 (1905). 



f. gracilis FoSL. 



1. c; tab. nostr. i, flg. 16 — 22. 



Syn. Lithoth. squarrulosum Heydr. Lithoth. Mus. Paris p. 541! 



Thouijh as yet only sterile specimens of this alga are known, I think it almost 

 unquestioiiable that it represents an independent species of the genus Lit/iothaiitnion. 

 It was probably first found by the Challenger-Expedition and was referred by DiCKIE ' 

 to Melobesia calcarea. In habit it no doubt very nearly approaches Lithoth. calca- 

 rcuin, and so it does also as to structure, though some scars I have found from 

 conceptacles emptied seem to suggest that in the latter respect it is more closely 

 connected with L. riigosinn. I have even seen specimens of these species, the ty- 

 pical forms of which are widely different. much approaching to each other also in 

 habit. It is, therefore, not improbable that L. heterocladum should be a species 

 proceeding from L. nigosum rather than from L. calcateuvi. 



There are two fornis of the species, a coarser one, f. crassa with the branches 

 about 3 — 4 mm. thick, and a finer one, f. gracilis, whose branches are about 2 — 4 

 mm. thick (PI. i, hg. 16 — 22). The former comes very near to Lithoth. pulchrum, 

 but is smaller. Cp. Siboga-Exp. LXI. pl. IV. (Jn the other hand, f gracilis ap- 

 proaches Lithoth. australe f tiialeiisis and f brachiata. Cp. 1. c. pl. II. 



Lithoth. Iiftcrocladum occurs in the sublitoral region. It is certainly alleged to 

 have been found in the litoral region in the Beagle Channel, but a couple of speci- 

 mens collected in this locality are likely to have been washed up from the upper 

 parts of the sublitoral region. At the Observatory Island it occurs in a depth of 

 about 14 fathoms, associated with IJthoth. riigosmn and other species, but also here 

 apparently in no great numbers. DiCKlE on the contrary states 1. c. : 'Tt forms 

 dense beds in Isthmus Harbour, Straits of Magellan, and was dredged in 8 fathoms." 



Area: Patagonian Channels: Isthmus Harbour, f. valida (Challenger-Exp.); 

 Smyth Channel, Puerto Hueno, f valida (V. PaeSSLER); Smyth Channel, Long Is- 

 land, f. gracilis (MiCH AELSEN); Beagle Channel, f. ^'•;7?rt7w (Skott.sberG); Observa- 

 tory Island near Staten Island (SkoTTSBERG). 



' DiCKlE. . Supplemental Notes on Algoe collected by H. N. Moseley, M. A., of 11. M. S. " Challen- 

 ger", from various localities. 4. .Vlga; from Port Louis, Falkland Islands, and Magell.in-Straits. — Journal 

 Linnean Society. Bot. Vol. 15. (1875 — 77^- l'^^g- 44^- 



Schwedische Südpolai-E.-cpedition igoi — igoj. 2 



