128 Mr. Lubbock on some Arctic species of Calanidae. 



and slender ; all the hairs are short except two, one on each side 

 of the apical segment. 



The second antenna, have the 6-jointed ramus rather longer 

 than the other. 



The third pair of maxillipeds are rather small, and consist of 

 6 segments, of which the basal has 10 setose hairs arranged by- 

 pairs. 



The natatory legs increase in size from the first, which are 

 only j J q inch in length, to the fourth, which are g-yth. The rami 

 are 3-jointed. 



The fifth pair (fig. 10) are small, q~ inch in length. They 

 consist of a basal segment, then a swollen part, which appears to 

 represent the second basal segment ; then a narrower part, pro- 

 bably homologous with the larger or outer ramus. It has a con- 

 striction in the middle, and bears three hairs at the apex, and a 

 short one externally at the middle. 



The abdomen 3-jointed, long, without the lamellae -^ of an 

 inch in length ; the lamellae themselves are -q-q, i. e. as long as the 

 preceding abdominal segment, and each bears 5 plumose setae, 

 4 at the end and 1 on the external side. 



In the basal segment of the abdomen is an oblong vesicle ; it 

 is present in all the species, but is very conspicuous in this one. 

 I neither know its structure nor its use, but from its position, I 

 imagine it is connected with generation. 



In passing I may remark, that Dr. Sutherland collected C. 

 arcticus from N. Lat. 59° to 78° 30', and from W. Long. 29° 30' 

 to 71° 37'. In several cases Dr. Sutherland remarks, that when 

 none were caught at the surface, after sinking the dredge two or 

 three fathoms, " hundreds were obtained in a few minutes/' The 

 colour is red. 



These species are on an average \ of an inch in length, which 

 is much larger than the average of the whole genus. The Arctic 

 seas therefore seem very favourable to the development of the 

 genus Calanus. The colour had in every specimen completely 

 disappeared. 



Note. — There is some confusion about the name Calanus. 

 The genus was founded by Leach, with the type C. Finmarchicus, 

 on erroneous characters. Dr. Baird, however, rinding, that though 

 Leach's reasons were ill-founded, others made it necessary to 

 erect it into a new genus, dropped Leach's name Calanus and 

 adopted a new one, Temora, for the same species. Dana in his 

 work on Crustacea uses the name Calanus, as 1 have done in this 

 paper. It is however doubtful whether the species which he and 

 I have referred to Calanus, really belong to the same genus as 

 C. Finmarchicus; there are no specimens of it in the British 



