Copepoda. 38 
from st. 28, 36° ON, W, 0—200 m. wire 
—»— 45, 28° 42’ N, 20° 0 W, 1000 —»— 
—»— 50, 30° 8 N, W, 500—1000 —»— 
—»— ,51, 31° 20’ N, 35° 7 W, 200, 1000 —»— 
St. 92 is situated S W of Ireland, St. 19 outside and St. 28 
inside the Gibraltar ridge, St. 45 west of the Canary isles and 
St. 50, 51 south of the Azores. 
The distribution of MH. acutifrons is very Eier, It is not 
likely that specimens from st. 92 and from the stations 45, 50, 
51 are referable to the same centre of distribution. At any rate 
it is impossible that the specimens at st. 19 in the western Me- 
diterranean should have been transported from the north, as the 
hydrographical conditions at the entrance of the Mediterranean 
preclude such a supposition. In the strait of Gibraltar there is 
an Atlantic inflow of water from 0 to about 50 m. to the Medi- 
terranean and from about 100 m. to the bottom there is an 
outflow to the Atlantic of Mediterranean water with great sali- 
nity’). Thus we are obliged to consider the western part of the 
Mediterranean as a centre of distribution for Haloptilus acuti- 
jrons and on this supposition, the occurrence of the species at 
several stations in the Atlantic west and south-west of the Gi- 
braltar strait is easily explained. According to a. scHotr (I. c., 
159) the high salinity of the Mediterranean is perceptible at 
a depth of 1000 m. at a distance of 800 km. south-west of the 
Gibraltar strait. Hydrographical investigations in later years 
have also shown that the under-current in the Gibraltar strait 
extends its influence along the coast of Portugal to the bay of 
Biscay and farther north to Ireland and Scotland. It seems, then, 
hardly beyond the limits of possibility that the occurrence of 
H. acutifrons at st. 92, south-west of Ireland, may be derived 
from the Mediterranean centre of distribution, but we are incli- 
ned to think that the occurrence at the said station is due to a 
northern centre, as the same locality also yielded the following 
species: Eucheta norvegica, Xanthocalanus borealis, Scapho- 
calanus magnus, Metridia longa, Heterorhabdus norvegicus, 
Mormonilla minor. These species do not beiong to the Medi- 
1) G. A. O. p. 159. 
