FKOM THE GULF OF GUINEA. 39 



Calocalanus plumulosus (Glaus). (PI. I. %s. 35, 36; PI. VI. figs. 7, 8.) 

 1863. Calanus plumulosus, Claus, Die freilebenden Copciioden, p. 174, taf. xxvi. figs. 15, 16. 

 1892. Calocalanus plumulosus, Giesbrecht, op. cit. p. 185, pis. 3, 9, 36. 



Length (female) 1-3 mm. Body elongate, first segment nearly equal to twice the 



entire length of the other three ; postero-lateral angles of thorax rounded. Anterior 



antennoe, reaching somewhat beyond the extremity of the abdomen, 24.-jointed; the large 



basal joint bears one long plumose seta near the proximal end, the last joint is slender 



and equal to the combined length of the preceding two. The proportional lengths 



of the joints are nearly as shown in the formula : — 



50 . 10 . 10 . 10 . 10 . 10 . 10 . 10 . 11 . 13 . 10 . 16 . 18 . IS . 18 . 19 . 18 . 21 . 21 . 21 . 21 . 20 . 15 . 36 

 i 2 3 4 5 7 8 10 11 12 13 14 15 16 17 18 19 20 21 2)i 23 24' 



Posterior antennae, mouth-appendages, and swimming-feet as in Calocalanus pavo. 

 The last joint of each foot of the fifth pair is equal to half the length of the foot, and 

 the third joint is nearly one and a half times the length of the preceding one ; the 

 broadly rounded extremity of the last joint bears a small spine near the outer ano-le a 

 much larger spine near the middle, and a moderately long seta near the inner ano-le • 

 there are also two small setae near the distal end of the inner margin ; both mar^-ins of 

 the joints are also more or less fringed with cilia (PI. I. fig. 35). Abdomen short, first 

 segment rather tumid, the second much shorter than either the first or third, breadth of 

 the second and third increasing towards the distal end ; the first and second have each a 

 fringe of small serrse concentric with, and a little anterior to, the distal margin. Stylets 

 about equal to the length of the second abdominal segment, slightly divergent, and 

 furnished with four terminal plumose setae, and one very small seta near the extremity 

 of the inner margin. 



Calocalanus plumulosus was obtained in a tow-net gathering from 30 fathoms, 

 lal. r 55' 5" N., long. 6° 55' 5" E., collected January 22ud. Only a few specimens were 

 observed. 



This species difi'ers very markedly, not only in its greater size but also in general 

 appearance, from Calocalanus pavo ; moreover, the anterior antennae are proportionallv 

 much shorter than in that species. The proportional lengths of the joints of the anterior 

 antennae and fifth feet also differ considerably in the two species. Another character of 

 the spirit specimens is the abruptly flexed abdomen, which is bent at a right angle in all 

 those obtained. The position of the caudal stylets in Calocalanus plumulosus is almost 

 normal, while those of Calocalanus pavo are extremely divergent. The long plumose 

 seta on the basal joint of the anterior antennae appears also to be a character of Caloca- 

 lanus plumulosus *. 



Genus Heterocalanus, nov. gen. (Provisional name.) 

 Anterior antennae 22-jointed ; right antennae of the male resembling that of the 



* " Dieser " (the long basal joint of the anterior antenna?) " triigt eine kraftige, zweiseitig befiederte, gelb 

 pigmentirte Borate." Claus, he. cit. 



