1897-98.] Prof. D’Arcy W. Thompson on Marine Faunas. 341 
Elasmobranchii. 
Raia . — Of this widely distributed genus, two species are 
known from, and peculiar to, Kerguelen. No characters are 
recorded in which these resemble European species more 
than those of the south and west of the American continent 
or of Japan. 
It appears from this, that of thirteen fishes that we know from 
Kerguelen, not one fish , and, with the exception of the cosmo- 
politan skate, no genus of fishes , extends its northern range beyond 
Neiv Zealand and the Falklands. 
The resemblance which Murray, following Gunther, has drawn 
between the fishes of the northern and the southern temperate 
zones is another problem altogether. Without entering further on 
this problem, I may refer at least to the two particular instances 
quoted by Murray, the genera Tracliichthys and Polyprion. 
Of Polyprion the northern species is exceedingly similar to, though 
less elongate than, the southern form, and the two are united in a 
single species by Goode and Bean. One or other occurs on both 
sides of the North Atlantic, at the Cape, at Juan Eernandez, and 
in the Australian region. The southern form of this deep-water 
fish has thus an immense range, and of the northern, Dr Gunther 
says (A. M. N. PL. (5), xx. p. 237, 1887), “we may well 
expect that P. cernium will be met with far beyond the limits of 
the North-eastern Atlantic.” Its discovery off Newfoundland 
(Goode and Bean, p. 239) is a beginning of this anticipated ex- 
tension of its range. 
Murray cites from Gunther the genus Tracliichthys, “by 
which the family Berycidoe is represented in the southern tem- 
perate zone,” as being “ much more nearly allied to the northern 
than to the tropical genera.” But the genus itself is both tropical 
and northern, for one species, T. Darwinii, Johnston, is from 
Madeira, and is said to be identical with T. japonicus, St. and D., 
from Japan, while T. intermedins, Hector, described from New 
Zealand, has more lately been discovered by Alcock in the Bay of 
Bengal {A. M. N. H. (6), iv. p. 380, 1889). 
Again, when the two genera, Sebastes and Agonus, are quoted as 
Arctic genera represented in the Patagonian region, we must 
