144 REPORT ON THE PELAGIC COPEPODA 



Report on the Pelagic Copepoda collected at Plymouth 



in 1888-89. 



By 



Gilbert C. Bourne, H.A., F.Ii.S., 



Fellow of New College, Oxford, and Resident Director of the Association. 



With Plates XI and XII. 



The Copepoda not only form the greatest part of the pelagic life 

 in temperate seas, but are also of the greatest importance in pelagic 

 economy. Feeding on minute organisms and particles of animal 

 and vegetable matter, they are themselves a prey to larger organisms. 

 Some fishes such as the herring, pilchard, and mackerel feed almost 

 exclusively on Copepoda at certain seasons of the year, and experi- 

 enced fishermen are accustomed to look on the swarms of Copepods 

 which make their appearance in the spring and early summer as 

 the sure precursors of a shoal of fish. The important part played 

 by these minute Crustacea in the change of material in the sea has 

 led me to pay particular attention to them amongst the other organ- 

 isms found swimming free at the surface or at difi^ei'ent depths in 

 the open sea. The following is a preliminary account of the species 

 which I have hitherto met with in the surface net collections made 

 during the past year. The systematic work necessarily precedes 

 the more laborious and thorough investigation of the life-history and 

 bionomy of the group which I hope to be able to enter into at a 

 later date, the present work, therefore, pretends to nothing more 

 than an enumeration of the species captured, and an indication of 

 their distribution. The species taken in the surface net amount 

 to sixteen, of which the majority, as might be expected, belong to 

 the Calanidse. Of the sixteen, nine species belong to this family, 

 two to the Cyclopidge, three to the Harpactidee, and two to the 

 Corycseidae. The majority are well known on British coasts, two 

 species which I have found in abundance, viz. Paracalanus parvus 

 and Euterpe gracilis, are generally considered rare in this country, 

 and Pontella wollastoni is a rare English form which I have found 

 sparingly. One species, Oncsea mediterranea, has not hitherto been 

 seen north of the Mediterranean. On the other hand, several well- 

 known species of Calanidae are altogether absent from my collections, 

 viz. Metridia armata, Isias claviyes, and Centropages hamatus. The 

 labour of looking through and sorting the large amount of material 



