1902-1903.] Daéstribution of the Smaller Crustacea. 5 
occasionally in June. The increase is rapid till the maximum 
is reached, and the subsequent decrease appears to be as rapid. 
This was due to the fact that these three months form the 
principal spawning period of this group of the crustacea. It 
is also shown in the same paper that though Calanus heligo- 
landicus, one of the more common of the marine copepoda, 
exhibited for the seven years scarcely any perceptible differ- 
ence in its distribution as the result of seasonal changes, the 
distribution of Temora longicornis showed, on the contrary, con- 
siderable diversity in the frequency of its: records for the dif- 
ferent months; and as this diversity occurred year after year 
with a certain amount of regularity, it was probably caused 
by the succession of the seasons, and the changes consequent 
thereupon. The maximum number of records for each of the 
seven years occurred in April and May; the records for the 
succeeding months, from June to October, were fairly regular, 
and were on an average scarcely half the number recorded for 
April and May; but the average monthly records from Nov- 
ember to March were only about two-fifths of the average 
for the previous five months. In other words, the average 
number of records for April and May was 51; for the five 
months from June to October, 23; but for the five months 
from November to March it was only 9. 
Second, The influence of currents on the distribution of the 
smaller crustacea. The species whose distribution is chiefly 
affected by currents are those usually described as pelagic or 
free-swimming ; and several interesting examples, exclusively 
marine, have been observed. One of the more prominent of 
these is the occurrence on the north and east of Scotland of 
Lucalanus crassus and Hucalanus elongatus. Eucalanus crassus, 
Giesbrecht, was described by Dr Giesbrecht in 1888, and it 
has been recorded by him off the east coast of South America, 
in the South Pacific, and in the North Atlantic up to latitude 
41° , as well as from the Mediterranean; and I have also 
obtained it in gatherings collected in a Gulf of Guinea. 
This species has on several occasions been taken in the Moray 
Firth, and on November 19, 1897, a considerable number of 
specimens were captured there; but though they included 
