T 



SPONGES 



By Maurice Burton, M.Sc. 



Assistant-Keeper, Department of Zoology, 

 British Museum (Nat. Hist.) 



(Plates XLVIII-LVII, text-figs. 1-56) 



INTRODUCTION 



HIS report is based on the study of material collected by the R.R.S. 'Discovery', 

 the R.S.S. 'William Scoresby' and the staff of the Marine Biological Station at 

 South Georgia during the years 1925-9. In many respects the collections obtained are 

 of unusual interest, including as they do specimens from the West African coast and 

 from the area around Tristan da Cunha, for our knowledge of the sponge faunas of these 

 two localities is as yet meagre. The rest of the material was obtained mainly from South 

 Georgia, South Shetlands, the Falkland Islands and the extreme southern part of the 

 South American continent. 



The sponges in these collections are abundant and well preserved and include re- 

 presentatives of 168 species and varieties, of which only 35 are new: but the more im- 

 portant feature of the collection is the fact that many of the species are each represented 

 by numerous individuals. Five species of Tedania, for example, are represented 

 by nearly 200 specimens of all sizes. When abundant material is to hand for 

 comparative study, it is always found that the prevailing ideas concerning the species in 

 question require radical revision. It has been possible to show here that the variations 

 in T. massa, Ridley and Dendy, go far beyond what might a priori have been 

 expected. Moreover, the extremes of fluctuation in the dimensions of the spicules, 

 within a given species, are considerably wider apart than has hitherto been thought to 

 be the case. This is strikingly demonstrated in lophon chelifer, Ridley and Dendy, in 

 which species again considerable quantities of material are available. 



In addition to the usual systematic studies, a certain amount of data is made 

 available from the identification of the Discovery collections concerning the develop- 

 ment and the breeding seasons of Antarctic species, and our knowledge of the distribu- 

 tion of species in the South Atlantic and Antarctic is considerably increased. 



SYSTEMATIC LIST OF SPECIES 



Sub-kingdom PARAZOA 



Phylum NUDA 



Order HEXACTINELLIDA 



Family ROSSELLIDAE 



Genus Rossella, Carter. R. villosa, Burton. 



R. antarctica, var. intermedia, n. Genus Gymnorossella, Topsent. 



R. nuda, Topsent. G. inermis, Topsent. 

 R. racovitzae, Topsent. 



