
80 THE NORTHERN MICROSCOPIST, 

to the fresh water and brackish water species, what shall we say 
with regard to the marine species when we find, by a careful 
study of the Challenger Expedition, how wide-spread indeed is this 
little Crustacean. 
The following is a short summary of ‘‘ The Challenger ” work 
as regards the subject in question. Out of the multitudes of Cypri- 
dzan forms taken on board, ten species were obtained from the 
North Atlantic, and ten from the South Atlantic ; six species were 
procured from the South Indian Ocean, and twenty-seven species 
from the Australian seas ; five species come from the South Pacific 
and six species from the North Pacific, while from Eastern Asia 
three species only were taken. 
The interesting fact follows that, of the various sedimentary and 
other deposits, in which the Cypris was found, mud seems to have 
been the most congenial, because in the West Indies, North Brazil, 
Bermudas, and Pernambuco, from depths ranging from 390 to 675 
fathoms, mud was in every case the sediment. Where formed in 
sand the depths were 38 to 4o fathoms only, while in one case only 
of coral at Tongatabu 18 fathoms was the depth. ‘The greatest 
depth from which the Cypris was procured is that of 1,452 fathoms 
off Tristan D’Achuna found in the globigerina ooze. Now as this 
globigerina ooze of the Atlantic is said to be not only an equivalent 
of the chalk deposits of the cretaceous period, but by many pre- 
sumed to be a continuous co-extension of that age—it shows that 
we are still in the chalk age. It would become an interesting study 
for some of our readers to work out, as far as practicable, the organic 
microscopic remains of this ooze, and see how far they agree with 
those of the chalk itself. Although the Cypris has been found in 
the globigerina ooze, or red clay of the Atlantic at such a great 
depth, it is remarked as being singular that it is generally wanting, 
as half the dredgings contain no trace whatever. 
The tow net was used at various stations, and as from twenty- 
nine dredgings at depths beyond 500 fathoms fifty-two species 
were taken ; at depths below 1,500 fathoms nineteen species only 
were taken ; and, further, when we find that of the shallow water 
dredgings—Booby Island twenty-eight, Port Jackson twenty-three, 
Torres Straits nineteen, and Balfour Bay nineteen species—it is 
obvious that our Cypris is zo¢ a lover of the great depths, but 
rather prefers the light of day. 
Although, of all the species taken in the seven areas of distri- 
bution named, only two species of Ostracoda were sufficiently 
pliant to live in all these areas, it is an interesting fact to find 
that it is possible for one or more species of such a minute crus- 
tacean to be able to adapt itself to the various temperatures. The 
two species were natatory pelagic, and are named Aadocypris 
Atlantica and Halocypris brevirostris, and Dr. Brady considers it is 
