460 PROFESSOR CHARLES CHILTON ON THE 
or by a closely allied form in the southern is also shown to be increased. Leaving out 
of account the species known to be cosmopolitan, it has been long known that there 
were some species identical in Arctic and Antarctic seas, though practically unknown in 
the tropics; nearly every writer on Antarctic Amphipoda has identified one or more 
with northern species. It appears from examples like Orchomenopsis chilensis 
(Heller), and others that might be quoted, that in these examples of ‘‘ bi-polar” species 
the species is not always entirely absent from the tropics, but exists there in deeper 
waters, while it can live near the surface in the colder regions; or that the tropical or 
temperate form is so much smaller than the polar one that it has usually been 
considered a separate species, and the existence of the species at intermediate localities 
has been overlooked. It appears that, for some reasons not altogether understood, many 
Amphipoda find their optimum environment near the Arctic and Antarctic regions, 
and exist there in greatest abundance, attaining a size far greater than that usual for 
The dithculty of deciding whether these smaller 
forms are to be considered separate species or not is very great, and it must not be 
expected in the present state of our knowledge that logically uniform results ean be 
arrived at. 
similar forms in warmer seas. 
In some cases where the animal is abundant and specimens from many 
localities have been examined, we may be able to group them into one large species, 
while in other cases where only a few have been studied we are forced to leave them as 
separate small species. Unfortunately, this leaves the groups distinguished by specific 
names of very unequal value in the discussion of questions of distribution. 
IJ. List oF SpEctss. 
ANTARCTIC AND SUB-ANTARCTIC. 
NAME OF SPECIES. 
DISTRIBUTION AND REMARKS. 
1. Acontiostoma marionis Stebbing. Gough Island, Marion Island, Straits of Magellan, New Zealand, 
2. Amaryllis macrophthalma Haswell. Australia, South Atrica, South America, New Zealand, 
Indian Ocean. 
3. Cyphocuris anonyx Boeck. Widely distributed in both northern and southern seas. 
4. Lysianassa cubensis (Stebbiug). South Africa and Gulf of Mexico. 
5. Alicella scotiz, sp. nov. South Atlantic ; an allied species found in the North Atlantic. 
6. Cheirimedon femoraius (Pfeffer). South Orkneys, South Georgia, and Graham Land (Port 
Charcot). 
7. Tryphosa murrayt Walker. Off Coats Land and South Victoria Land. 
8. Tryphosites stebbingt (Walker). Off Coats Land and South Victoria Land. 
9. Orchomenella pinguides Walker. South Orkneys and South Victoria Land. 
10. Orchomenella macronyx Chevreux. South Orkneys and Graham Land (Port Charcot). 
1l. Waldeckia zschauti (Pfeffer), Off Coats Land, Graham Land, and South Victoria Land. 
12. Orchomenopsis nodimanus Walker. South Orkneys and South Victoria Land. 
13. Orchomenopsis chilensis (Heller). In all seas, northern and southern, 
14. Orchomenopsis (?) coats, sp. nov. Off Coats Land. 
15. Harpinia oblusifrons Stebbing. Widely distributed in Antarctic and sub-Antarctic seas. 
16, Leucothoe spinicarpa (Abildgaard). In all seas, 
17. Amphilochus squamosus G. M. Thomson. South Orkneys, Marion Island, and New Zealand. Perhaps 
identical with A. neapolitanus of northern seas. 
