REPORT ON THE COPEPODA. 33 



hitherto noticed, I believe, by any author, are equally well developed in the typical 

 Calanus jinmarcliicus of the North Sea. Such examples as have usually come under 

 my notice, taken off the east coast of England, or in other places very near to the English 

 coast, are comparatively small, and have their salient characters not strongly marked ; but 

 I have recently had the opportunity of examining specimens collected in more northern 

 latitudes, during the cruise of the "Knight Errant," 1 and I cannot see that these differ 

 in any respect from the southern form. Thus, the only reasonable course is to consider 

 both the northern and southern forms as belonging to one species, probably the most 

 abundant and most widely distributed of. all the Copepoda. In the arctic regions it 

 is known to be very abundant, and the specimens described by Roussel de Vauzeme 

 from the antarctic seas are identically the same. I do not know, however, of its occur- 

 rence in the warm seas of the tropics. 



Though this species has already been frequently described and figured, I have 

 thought it best to give drawings of some of the most distinctive characters as seen in 

 southern specimens. The figures have all been drawn by aid of the camera lucida. 



2. Calanus valgus, n. sp. (PL III. figs. 1-7). 



Length, l-7th of an inch (3 '5 mm.). Forehead broadly rounded, rostrum long and 

 slender ; head incompletely separated from the thorax (fig. 1). Anterior antenna 

 rather longer than the cephalothorax, its setae distributed as in Calanus jinmarcliicus. 

 Posterior antennas and mouth organs as in Calanus jinmarchicus. Swimming feet very 

 long and slender, their marginal spines longer than in the preceding species. The 

 right fifth foot of the male (fig. 5) is not very much longer than the left, but the 

 marginal spines of the first and second joints are very long, — longer indeed than the 

 joints themselves; the third joint bears a comparatively short apical spine; the inner 

 branch is destitute of setae, but bears small marginal spines ; the foot of the right side 

 (at any rate in spirit specimens) is usually flexed at a right angle, as shown in fig. 6 ; 

 basal joint of the peduncle finely serrated on the inner margin. All the joints of the male 

 abdomen are nearly equal (fig. 7), but in the female (fig. 1) the first two joints are much 

 longer than the following two. 



Habitat. — Off Cape Howe, Australia, at night ; in the Arafura Sea, in several South 

 Pacific Stations (287, 288, 295, 296, 299) between lat. 38° S., long. 94° W., and lat. 33° 

 31' S., long. 74° 43' W. ; in lat. 36° 9' S., long. 48° 22' W. (Station 324, South Atlantic), 

 and in lat. 3° 10' N., long. 14° 51' W. (Station 348, North Atlantic). The gathering from 

 Station 296 consisted entirely of this species, and in several others it was also tolerably 

 abundant. 



1 Exploration of the Faroe Channel during the summer of 1880, in Her Majesty's hired ship " Knight Errant," 

 Staff-Commander Tizard and John Murray, Froc. Roy. Sue. Edin., vol. xi. pp. 638, et seq. 1882. 



(ZOOL. CHALL. EXP. PART XXIII. — 1883.) Z 5 



