146 EEPORT ON THE PELAGIC COPEPODA 



Pabacalanus paeyus, I. C. Thompson. Copep. of Liverpool Baj', Proc. Liv, 



Biol. Soc, ii, p. 64. 



This species appears to liave been taken only once before in 

 England, viz. by the Liverpool Marine Biology Committee in 1888. 

 Canu found it in abundance at Wimereux. I cannot consider it as 

 a rare species at Plymouth for I have found it in great abundance 

 in several gatherings and less abundantly in many others. Appa- 

 rently it is absent from these coasts in the winter, for I could not 

 find a single specimen in gatherings made between September and 

 March. I have not observed the disproportion in the numbers of 

 males and females described by Canu. This species is easily recog- 

 nised by the form of the first antennae of the male, by the serration 

 of the external edges of the outer branches of the swimming feet, 

 and their simple spines in both sexes, and by the characteristic shape 

 of the fifth feet in the male and female. The characteristic ensiform 

 and plumose terminal seta3 of the second maxillipedes of the male 

 appear to have been overlooked by previous observers, vide PL XI, 

 fiff. 3. 



3. Clausia elonqata, Boeck. 



PSEtTDOCALANtrs ELONGATTTS, Brady. Monogr., Brit. Copep., i, p. 45, pi. iii. 



— — Giesbrecht. Freileb. Copep. der Kieler Foehrde, 



Naclitrag. 



— — I. C. Thompson. Proc. Liv. Biol. Soc, ii, p. 63. 

 Clausia elongata. Clans. Neue Beitrage ziir Kent, der Copep., Arb. Zool. 



Inst. Wieu, iii, 3, p. 16, Taf. iii, figs. 11—15. 

 Lucuiius ACUSPES, Giesbrecht. Freileb. Copep. der Kieler Foehrde, p. 160. 



This is one of the commonest species in the Plymouth district. 

 I have taken it in autumn, winter, and spring in immense numbers. 

 The absence of the fifth pair of feet in the female, and the form of 

 the fifth feet of the male are characteristic features of this species. 

 Young males are frequently very abundant, and as Claus has pointed 

 out (loc. cit.), they differ from the perfect males both in the form of 

 the fifth feet and in other particulars, so that they might easily be 

 mistaken for a distinct species. Giesbrecht in the body of his 

 work, quoted above, refers Clausia elongata to a new genus and species, 

 Luriilhis acuspes, but withdraws this name in an appendix. It is 

 difficult to understand how he can have overlooked the identity of 

 his specimens with Pseudocalanns elongatus, Boeck ; described by 

 Brady, since the latter's figures of the fifth pair of feet of the male 

 are readily recognisable, defective as his description may be in some 

 particulars. I. C. Thompson in a report of Copepoda collected in 

 Maltese seas, refers to Liicullus acuspes, Giesbrecht ; and Pseudo- 



