2 W. A. HERDMAN. 
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., Molgula hodgsoni, measuring 
4 cm., and Halocynthia setosa wp 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 Ascidiide and Molgulide, while 
tropical seas have more Cynthiide. 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 
* Expédition Antarctique francaise (Charcot). Tuniciers. Paris, p.1. 
