386 



TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



this year, as follows : — April 18th, 100; September 1st, 20; 

 September 4th, 20. So the species is now of no quantita- 

 tive importance in our district, and we only give its record 

 this year, because of the probably quite exceptional 

 invasion or increase which took place in 1907, and which 

 first drew our attention to this otherwise rare form. 



The monthly average hauls for the eight more 

 important species of Copepoda are as follows: — ■ 



1913. 



Calanus. 



Pseuclo- 

 calanus. 



Temora. 



Centro- 

 pages. 



Anomal- 

 ocera. 



Acartia. 



Oithona. 



Para- 

 calanus. 



Jan. 



6 



859 















262 



2,722 



247 



Feb. .. 



6 



1,134 



8 











209 



1,954 



370 



Mar 



6 



2,480 



181 



3 







374 



2,347 



299 



Apr. .. 



1 



3,681 



1,757 



56 



29 



755 



1,849 



17 



Mayj .. 



14 



4,030 



859 



52 



177 



4,367 



1,478 







June . . 



638 



16,944 



9,424 



235 



112 



14,399 



10,090 







Julyj 1 .. 



1,219 



5,874 



2,916 



165 



6 



9,282 



34,577 



50 



Aug. .. 



77 



6,768 



1,302 



34 







4,840 



16,583 



139 



Sept. .. 



436 



9,273 



296 



19 







8,180 



12,966 



7,886 



Oct. .. 



57 



3,236 



34 



9 







1,314 



8,391 



6,456 



Nov. . . 



17 



3,134 



2 



2 



1 



1,683 



18,291 



7,489 



Dec. | .. 



15 



1,013 



11 











168 



4,375 



2,668 



It seems unnecessary to repeat the diagram we gave 

 last year showing the curves for the chief genera of 

 Copepoda. It is true that the curves in some cases take a 

 slightly different form this year, but the columns of the 

 table enable one at a glance to see what the curve will be 

 like, where the maxima occur, and to what extent the 

 genera agree or differ in their distribution throughout the 

 year. Paracalanus, for example, has its minimum at the 

 time of the maximum of Pseudocalanus. 



Cladocera. 



The numbers for this group are not so high as in 

 previous years. As before, the Cladocera are a summer 

 group, only showing, as a rule, between April and 

 September. 



