[McmuRRICH] PLANKTON OF BRITISH COLUMBIA COAST 79 
mately 10:4:5. The genital segment bears upon its ventral surface 
at the anterior border a simple, backwardly directed hook, and on 
each side, in the neighborhood of the genital pore in both sexes there 
is a simple seta, and medial to this a short spine (fig. 4). The first 
antenne are six-jointed, and do not present any distinctive features, 
but in the second antennæ the terminal seta is much prolonged and 
decidedly curved and terminates in a blunt extremity (fig. 5). The 
seta on the second basal joint isa little shorter than that on the first 
joint and is finely serrate, whereas the latter is simple. The terminal 
joint of the exopodites of the 1-3 thoracic legs bears three sete of 
the usual form on its outer border, and the terminal seta of the second 
pair is straight and not curved inwards to any appreciable extent. 
(fig. 6). The endopodite of the fourth pair of thoracic legs is reduced 
to a small tubercle, which bears two long feathered sete, and in some 
examples is clearly divided into two portions. (fig. 7). 

Fig | Fig J 
Fig. 5. Second antenna of Corycaeus affinis ©! 
Fig. 6. Second thoracic limb of Corycaeus affinis © 
Fig. 7. Fourth thoracic limb of Corycaeus affinis © 
The two setae borne by the rudimentary endopodite of the fourth 
pair of legs indicate a close relationship of this species to C. tenuts 
Giesbr. and C. Zubbockii Giesbr., both of which are Pacific forms, 
tenuis occurring in the equatorial region and lubbockii in the neigh- 
borhood of Hongkong! From both these forms, however, C. affinis 

1 W. Giesbrecht. Elenco dei Copepodi pelagici raccolti dal tenente di vascello 
G. Chierchia durante il viaggio della R. Corvetta ‘‘Vettor Pisani’’ negli anni 1882- 
1884, e dal tenente di vascello F. Orsini nel Mar Rosso, nel 1884. Atti Accad. Lincei 
Roma. Ser IV. VII. 1891. 
