ISOPODA. 3 



it would have been more appropriate to make the provinces coincide with the oceans to 

 the north. It may be so, but it seems to me to name the provinces from the point 

 of attack is the wisest course in the present state of our knowledge. The more I see 

 of the South Polar fauna the more certain I become that a very large proportion of 

 species have a circumpolar distribution. It would also appear that the northwardly 

 projecting spur of Graham's Land, which passes for some considerable distance beyond 

 the Antarctic circle, constitutes a barrier round which species have a difficulty in 

 passing. Whether the South Polar fauna originated in those latitudes and has spread 

 northwards, or whether it has acquired its present aspect by migration from the north, 

 is a speculation which will be material for discussion for many years to come. Be this 

 as it may, our greatest knowledge will lie nearest to the three points of attack, and 

 from these it will be comparatively simple to investigate the passage of various species 

 northwards into the great oceans. A circumpolar fauna will specialise more or less 

 distinctly as it passes northwards, and its ancestors or other relations become separated 

 by the great land masses. Or, if investigation shows the migration to be in a southerly 

 direction, we have in those oceans three independent streets down which the fauna 

 passes to mix beyond their junctions, or to pass on to the uttermost limit where 

 uniform conditions, within certain limits, must have their effect. 



The collection brought back by the ' Frangais ' from the west coast of Graham's 

 Land is very like that of the ' Discovery,' no less than eight species are common to 

 both, their total number being thirteen. 



The collection of the ' Scotia ' is still in my hands for description, the shallow 

 water and littoral forms come from a more northerly latitude, the South Orkneys, the 

 deep sea forms from the Weddell Sea. I can only say here that this collection does not 

 contain a single species taken by the ' Discovery.' Three other Antarctic collections 

 remain to be described ; how far they will bear out the opinion expressed above remains 

 to be seen. 



Antarctic. Sub-Antarctic. 



Apseudes antarctica Beddard ...... X 



spectabilis Studer ....... X 



Tanais willemoesi Studer ....... X 



hirsutus Beddard ....... X 



Typhlotanais kcrguelenensis Beddard ..... X 



Leptognathia australis Beddard ...... X 



Nototanais dimorphus Beddard ...... X 



antarcticus Hodgson ...... X 



Paranthura neglecta Beddard ...... X 



* Leptanthura glacialis ........ X 



* Gnathia antarctica Studer ..... . X X 



tuberculosa Beddard ...... x 



* Euneognathia gigas Beddard ...... X X 



^Ega'magnifica Dana ...... . X 



semicarimita Miers ...... 



punctulata Miers ... 



,, edwardsi Dollfus ....... X 



H 2 



