1 902-1903.] Distribution of the Smaller Crustacea. 27 



. in the Firth of Forth, occurred during April and May, and 

 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 Teniora 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 

 Eucalamhs crassus and Uttcalamis clongatus. Eucalanus crccssus, 

 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 the 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 



