CALANUS. 39 



branch consisting of two joints, the inner of seven, 

 four of which are very short ; the inner branch bears 

 long marginal hairs along almost its entire length. 

 The basal joints of the fifth pair of feet in both sexes 

 are minutely serrated on the inner margin (fig. 8). 

 The fifth pair of feet in the female are like the 

 preceding pairs, but in the male (fig. 11) have the first 

 and second joints of the outer branch greatly elongated 

 and are devoid of marginal hairs, the third joint being 

 small, pear-shaped, and provided only with a couple of 

 minute spines at the apex. The terminal spines of the 

 swimming feet (fig. 10) are long, awl-shaped, and 

 destitute of serratures or hairs. Tail setae about as 

 long as the abdomen. Length of the animal, including 

 tail setae, about one sixth of an inch (4 mm.). Colour 

 variable, sometimes almost pellucid, at others yellowish 

 or dark red ; the body is often loaded with large 

 highly refracting oil globules. 



This species is found, often in immense numbers, all 

 round our coasts both in the open sea and between tide 

 marks, more especially in the early summer months. 

 It is essentially a pelagic species, loving the clear ocean 

 and not often to be met with in any great numbers 

 amongst weeds. It appears to be generally distributed 

 in the Arctic Ocean, the North Atlantic, and the 

 European seas, and I have seen specimens collected by 

 Mr. Eaton in the southern hemisphere, which are in 

 no respect distinguishable from the northern species, 

 though possibly identical with one considered specifi- 

 cally distinct by R. de Vauzeme.* It has been said to 



* ' Annales des Sciences Naturelles,' 1834. 



