GEOGRAPHICAL DISTRIBUTION 147 



angular outline or the inorganic nature of the sand grains allows them to be detected and prevented 

 from passing to the stomach. 



Remarks. This new species does not fit readily into any of the existing genera of the Molgulidae. 

 It is, however, in fairly good agreement with Eugyra as defined by Michaelsen (1915), Hartmeyer 

 (1923) and van Name (1945) differing principally in (1) the flat instead of conical stigmata, and 

 (2) the position of the left gonad in the secondary instead of the primary gut-loop. The structure of 

 the branchial sac is in general that of a Eugyra. Characteristically Eugyra has the left gonad within the 

 primary gut loop, but in some species it is only partially within the loop. The condition in E. drnbackae 

 therefore represents a further stage in the shifting of the gonad out of the primary loop. The possession 

 of a stalk, while not common in the genus, is known also in the Arctic species E. pedunculata Traustedt. 



Distribution. Antarctic (South Sandwich Islands). 



GEOGRAPHICAL DISTRIBUTION 



The ascidians have certain biological similarities to the sponges, particularly the sessile habit of the 

 adult, and the short pelagic life of the larva which lasts for about a day in both groups. These are two 

 characters greatly influencing the geographical spread of species, and it is therefore of interest to 

 analyse the distribution of the ascidians in the same way as Burton (1932) has done for the Antarctic 

 sponges. Table 38 gives the geographical distribution of all the ascidian species identified in the 

 1 Discovery ' collections. 



The three main Antarctic and Subantarctic areas in which ascidians were collected are (1) the 

 Graham Land region, (2) South Georgia, and (3) the Falkland Islands and Patagonian Shelf. For 

 each of these areas and also for the remaining part of the Antarctic continent, I have shown below the 

 numbers of species which are also found in the other principal Antarctic and Subantarctic regions : 



Antarctic continent, excluding Graham Land region, number of species 23 



Of these, number also at Graham Land 20 



S. Georgia 11 



Falkland Islands and Patagonian Shelf 5 



Kerguelen 6 



Campbell, Auckland and Macquarie Islands 2 



Graham Land region, number of species 23 



Of these, number also at Antarctic continent excluding Graham Land region 20 



South Georgia 12 



Falkland Islands and Patagonian Shelf 7 



Kerguelen 7 



Campbell, Auckland and Macquarie Islands 2 



South Georgia, number of species 32 



Of these, number also at Antarctic continent excluding Graham Land 12 



Graham Land 12 



Falkland Islands and Patagonian Shelf 15 



Kerguelen 14 



Campbell, Auckland and Macquarie Islands 3 



Falkland Islands and Patagonian Shelf, number of species 24 



Of these, number also at Antarctic continent excluding Graham Land region 5 



Graham Land 7 



South Georgia 15 



Kerguelen 8 



Campbell, Auckland and Macquarie Islands 5 



19-2 



