37° 



DISCOVERY REPORTS 



together in an endeavour to determine the breeding seasons for sponges in the Antarctic. 

 It is clear that the records are by no means sufficiently complete to be able to draw 

 definite conclusions from such a table; but the tentative deductions are interesting. In 

 the first place, there does not appear to be any part of the year during which a majority 

 of species are in a state of reproduction. The table shows that so far as can be told from 

 the available evidence some species are breeding at all times of the year ; but, as none of 

 the specimens investigated were littoral, there is perhaps little surprising in this. Secondly, 

 there is an indication that all or most species of Calcarea breed throughout the year, for 

 although the number of specimens examined is relatively small, the number of records of 

 ova and embryos is comparatively high. This might be said of the Euceratosa also. 



Comparison with the breeding seasons in the northern hemisphere is difficult, partly 

 again because of the paucity of observations (many authors have described embryos but 

 omitted to give the date when they were seen), and partly because the records here are 

 mainly from littoral or shallow-water specimens, whereas the Antarctic records are 

 mainly from deeper water (down to 500 m.). Nevertheless, we again find that the 

 Euceratosa are in a state of reproduction throughout the year, and again a suggestion 

 that the same may be true of the Calcarea (cf. Sycon raphamis, Schmidt ; see table given 

 below). Further, there is a marked breeding period from approximately May to October. 



Table showing the approximate breeding seasons of the European 

 and North Atlajitic species of sponges. 



Species 



Calcarea 



Sycon ciliatum (Fabricius) 



5. raphanus, Schmidt 



Grantia compressn (Carter) 



Leuconia aspera (Schmidt) 

 Tetraxonida 



Oscarella lobiilaris (Schmidt) 



Halicluna ocitlata (Pallas) 



Mycale contarenii (Bowerbank) 



M. minima (Waller) 



Myxilla inctustans (Johnston) 



Hymedesmia diijardini, Johnston 



Halichondria panicea (Pallas) 



H. bozcerbanki, Burton 



Hyyneniacidon caruncula, Bowerbank 



Tethya aurantiiim, Pallas 



Cliona celata, Grant 

 Euceratosa 



Spongia officinalis, Linnaeus 



Hippospongia equina, Schmidt 



Hircinia variabilis, Schulze 



Halisarca diijardini, Johnston 



Jan. 



Feb. 



Mar 



Apr. 



May 



June 



July 



Aug. 



Sept. 



Oct. 



Nov. 



In the one case, Oscarella lobularis (Schmidt), of a species common to the North 

 Atlantic and the Antarctic (in which the breeding season is known) it is found that the 

 same season is occupied in each locality. Thus, in the northern hemisphere, this 

 species is, presumably, reproductively active from June to November, and in the 

 Antarctic, from August to December. 



Dec. 



