IV. — Supplementary Report on the Hydroids of the Scottish National Antarctic 

 Expedition. By James Ritchie, M.A., B.Sc, Natural History Department, The 

 Royal Scottish Museum. Communicated by AV. S. Bruce, LL.D. 



(MS. received December 8, 1908. Read January 4, 1909. Issued separately May 27, 1909.) 



Since the report on the Hydroids collected by the Scotia was completed, almost 

 three years ago, I have had an opportunity, thanks to the kindness of Dr W. S. Bruce, 

 of looking through the enormous mass of material brought together by him during his 

 Antarctic voyages. The search, begun in the hope of finding a few minute species — 

 which, since many are epizoic on other forms of marine life, might readily be overlooked 

 on cursory examination — has resulted in the addition of no less than 25 forms to the 

 36 already recorded. Deducting from this total of 61 forms two varieties, it appears 

 that the Scotia collection contains in all 59 distinct species. Few, indeed, of these have 

 been obtained in truly Antarctic latitudes — subantarctic or temperate seas having 

 furnished the greater number — but this result is in accordance with the findings of the 

 majority of the recent Antarctic expeditions.* Dr Billard, in summarising the results 

 of the Belgian, Swedish, and French expeditions, states that the known Hydroid fauna 

 of Antarctic regions comprises only 32 species. But from his list he has, I think un- 

 justly, excluded South Georgian records. His list, moreover, published before the 

 valuable paper by Professor Higkson and Mr Gravely on the Discovery Hydroids was 

 issued, necessarily makes no reference to the large number of forms recorded by them 

 from Victoria Land. 



The following figures indicate the wealth in species of the Hydroid fauna of Antarctic 

 seas, the Antarctic area being defined as the region lying in ' ' higher southern latitudes 

 than the extreme limit of floating ice, according to the most recent research " (Bruce, 

 1894, p. 208); that is, an area corresponding to the Antarctic Circumpolar Subregion 

 of Ortmann (1906). To this region belong the 14 sjjecies collected by the Belgian 

 expedition (Hartlaub, 1904), 24 of the Swedish collection of 50 species (Jaderholm, 

 1905), the 8 species of the French expedition (Billard, 1906, ^^^), and 24 of the 25 

 English records (Hickson and Gravely, 1907). From the same area the Scotia 

 obtained only 9 species, although some of the most fruitful stations, Burdwood Bank, 

 the Falkland Islands, and Gough Island, lay just beyond its boundary. Extracting 

 the distinct species from those lists, we find that their number amounts to 68. 



The Hydroid Zoophytes, then, are represented in the Antarctic circumpolar seas, 



* The report on the Hydroids of the German expedition has not yet been published. 

 TRANS. ROY. SOC. EDIN., VOL. XLVIL PART I. (NO. 4). 9 



