2 W. A. IIERDMAN. 



characterised by the abundance and the large size of the individuals of a comparatively 

 few species. Every collection that has been brought home from the Antarctic since 

 has demonstrated the correctness of this conclusion, and I find that Dr. Sluiter, in a 

 recent publication,* draws attention to the same set of facts. The aspect, for example, 

 of the present collection, with its comparatively few species, is in marked contrast to 

 that of a collection from the Indian Ocean, or any other tropical or sub-tropical region,' 

 where the species are numerous and small. In the present collection as large 

 specimens we have Styela spectabilis, measuring 18 cm., Molyula hodgsoni, measuring 

 4 cm., and Halocynthia setosa up to 10 cm. ; while in the collection of the Scottish 

 Antarctic Expedition, now in my hands, this appearance of a fauna characterised by 

 few but gigantic, species is still more marked. This possession of unusually large 

 species is a character in which the far southern seas certainly seem to surpass 

 those of the far North. The Arctic Tunicate fauna, which is now so very much 

 better known than the Antarctic, shows no such marked assemblage of gigantic 

 forms. 



Although so many expeditions have collected in Antarctic seas of late, it cannot 

 be said yet that the fauna is sufficiently well known, as several of the collections have 

 not yet been worked out. We have reports upon the ' Valdivia,' the ' Charcot,' and 

 the ' Southern Cross ' Tunicata, but those of the ' Belgica,' the ' Scotia,' and the 

 ' Gauss ' are not yet published. There will undoubtedly be a certain amount of 

 overlapping in the collections from these various expeditions, but each will probably 

 add something to our knowledge of the Antarctic Tunicata. That knowledge is not 

 yet sufficiently detailed to permit of a close comparison with the corresponding Arctic 

 fauna ; but a certain similarity in families and genera which does not, however, 

 extend to identity of species is noticeable. For example, amongst simple Ascidians, 

 both polar regions are characterised by the presence of Ascidiidse and Molgulidse, while 

 tropical seas have more Cynthiidse. Other resemblances might be pointed out, but 

 I believe the time has not yet come to make a detailed analysis of the two polar 

 faunas. 



One difficulty met with in attempting any record of a section of the Antarctic 

 fauna is the absence of any natural northern limit and the want of agreement as to 

 where such a limit should be arbitrarily placed. 



If we take the Antarctic region in a wide sense as including the Strait of Magellan, 

 Tierra del Fuego, the Falkland Islands and Kerguelen Island, then we have a large 

 recorded fauna belonging to all groups of the Tunicata and characterised by abundance 

 of specimens belonging to many species (see, for example, those collected during the 

 ' Challenger ' expedition). If, however, we use the term ' Antarctic ' in a more 

 restricted sense, as including only the sea-area south of, say, 60 S. latitude, then we 

 cut out all land except the shores of the Antarctic continent itself; but even from this 

 restricted region some fifty species of Tunicata are already known. The following 



* Expedition Antarctique francaise (Charcot). Tunicicrs. Paris, p. 1. 



