THE RIGHT WHALE OF THE NORTH ATLANTIC. 895 
other beaked whales found in the southern hemisphere. In a memoir on the skull of 
Ziphius cavirostris from Shetland,* I compared it with the descriptions of beaked 
whales from the south of the Equator named by Gray Petrorhynchus capensis, by 
BurMEIstER EHpiodon australis, and by vAN BENEDEN Ziphius indicus, and I came to the 
conclusion that they were only southern forms of the Ziphius cavirostris obtained by 
Cuvier in the Mediterranean and by myself from Shetland. In my Challenger Report 
on the bones of the Cetacea ¢ I described the skull of a beaked whale from the Chatham 
Islands, which Sir James Hector had originally named Epiodon chathamiensis. I 
compared it with the Shetland skull, and came to the conclusion that they were of the 
same species, though one had lived in the far north and the other many degrees south 
of the Equator. I also noted that, since my first memoir on Ziphius was published in 
1872, vAN BENEDEN and Hector had accepted the view that the southern as well as the 
European crania of Ziphius were all examples of one species. I do not know if this 
whale has been caught in the tropics, but in my examination of the ear-bones collected 
by the Challenger and brought by the dredge from the floor of the ocean, I identified a 
tympanic bone obtained at 2275 fathoms in lat. 29° 35’ S. as identical in characters 
with that of the Ziphius cavirostris from Shetland. 
A wide geographical distribution prevails with Sperm Whales (Physeter macro- 
cephalus). They are caught in the temperate seas of New Zealand, also as far north 
as Shetland and the Faroe Islands,§ they are regularly hunted in the intermediate 
tropical seas, and no evidence of specific distinction exists between them whatever be 
their habitat. To all appearance, the great Sperm Whales are descended from a common 
ancestry. When oceans communicate directly or indirectly with each other, an oppor- 
tunity is given to the Cetacea to make an extensive migration, which for them, as for 
other migratory animals, seems to be mainly determined by the amount and nature of the 
food-supply, which in the Right Whales consists of plankton organisms, mostly minute 
erustacea, and in many other Cetacea of either cephalopods or small fish.|| Differences 
in habitat therefore do not necessarily imply specific difference, and on this ground no 
sufficient reason exists why the smaller Right Whale of the Kuropean and American 
coasts of the North Atlantic should not be the same species as the Balena australis of 
the southern hemisphere. No adequate evidence has been given to prove the presence 
of this whale, so characteristic of temperate waters, in the seas of the tropics. 
In the concluding volume of the Reports 1 of the Challenger Expedition, Sir JoHNn 
Murray has collected and analysed the results obtained from the sounding, dredging 
and trawling stations. He has shown that numerous species of Invertebrata, identical 
in character, were found in both the Arctic and Antarctic Oceans, and that a similarity 
of species existed in certain invertebrates from the temperate zones of the seas north and 
* Trans. Roy. Soc. Hdin., vol. xxvi., 1872. + Zoology, part iv., 1880. 
t See plate ii. figs. 9, 10, in my Challenger Report on the Bones of Cetacea, part iv., 1880. 
§ Proc. Roy. Soc. Hdin., vol. xxiv., 1903. 
|| The Killer Whale, Urea gladiator, is a flesh-eating cetacean, for it attacks and devours seals and porpoises. 
J Summary of Results, 2nd part, 1895. ‘ 
