1897 - 98 .] Prof. D’Arcy W. Thompson on Marine Faunas. 317 
Flabellum apertum, Moseley. — Recorded in the Challenger Report 
from Prince Edward Island near Marion Island, and from the coast 
of Portugal. The many very similar species of this genus come 
from Patagonia, Japan, Australia, the Philippines, the North 
Atlantic, and elsewhere. 
Holotliuria Thomsoni, Theel. — This species is represented by a 
single incomplete specimen from 1875 fathoms south-east of Yo- 
kohama Pay, and three others from 2900 fathoms, lat. 35° 22' N., 
long. 169° 53' E., due east of the same locality. The latter speci- 
mens are said to “ deviate in some degree from the diagnosis, and 
in some respects they are more nearly allied to the preceding 
species ( H . ladea)” A single small specimen obtained from 1800 
fathoms, lat. 50° 1' S., long. 123° 4' E. (due south of Australia), 
is described in regard to certain of its peculiarities sunder the name 
of H. Thomsoni, var. hyalin a , var. nov. ( Rep ., p. 185), by Dr 
Theel, who says that he proposes “ for the present to consider the 
specimen in question as a variety of H ’. Thomsoni.” 
Professor H. Ludwig, in a paper, which I have not seen 
(“Hamburger Magalhaenische Sammelreise,” Holothuriden, 1890, 
p. 90), quoted by Ortmann {Science, viii. p. 516, 1898), says, in 
regard to the supposed bipolarity of the Holothurians, that “ not 
a single species of the Antarctic fauna is represented in the Arctic 
fauna,” and that “there is not even a resemblance of both faunas, 
but a great dissimilarity.” 
Elpidia glacialis, Theel. — Of this species, well known and even 
abundant in the Kara Sea and the North Atlantic, the “ Chal- 
lenger” brought home a single specimen from 2600 fathoms, in 
lat. 42° 42' S., long. 134° 10' E. The species has a great range in 
depth, from 50 to 2600 fathoms, as well as in geographical dis- 
tribution. “ The southern form differs in various points from the 
northern ones, but the difference is of very little importance ” 
(Theel). 
Euphronides depressa, Theel. — One specimen from 1090 fathoms, 
lat. 35° 47' N., long. 8° 23' W., off Gibraltar; two specimens from 
1375 fathoms, 33° 42' S., 78° 18' W. This is another very 
remarkable form of a very remarkable group. The southern 
specimens are said to have differed considerably from the single 
northern one ; they were nearly three times as large, and for 
