62 BRITISH COPEPODA. 



the segments separated from each other by deep inden- 

 tations ; the joints of the abdomen, except the first, are 

 extremely small, the whole abdomen being only equal 

 in length to the second and third thoracic segments ; 

 caudal segments scarcely longer than broad; apical 

 setae five, three very short, the longer of the two 

 principal equal to about half the length of the body. 

 Anterior antenna 10-jointed, slender, of about equal 

 width throughout (fig. 2), almost destitute of setse 

 except at the apex, which is furnished with several 

 small, and two or three moderately long, setse, and 

 also with a slender olfactory appendage ; the relative 

 lengths of the joints as in the following formula : 



1,_2, 3, 4, 5, 6, 7, 8, 9, 10. 



10 17 3 3 8 3 9 6 7 15 



The extremities of the two limbs of the siphon are 

 somewhat lancet-shaped (fig. 3 a, a) and ciliated, and 

 the end of the mandible (V) is denticulated on one side. 

 The anterior foot-jaw (fig. 5) has a small subsidiary 

 claw near the apex, and the second joint of the poste- 

 rior pair (fig. 6) is ciliated along the outer margin. 

 Maxilla composed of two very slender digits (fig. 4), 

 each of which has two apical setaa, the shorter of the 

 two being marginally ciliated. The outer margins of 

 the first and second joints of the swimming-feet are 

 straight and fringed with closely-set short cilia, the 

 angles armed with two stout lancet-shaped spines, the 

 joints constricted at the proximal, and dilated at 

 the distal, extremity; last joint ovate, bearing three 

 spines on the outer, five long setas on the inner margin, 

 and a long finely denticulated spine at the apex ; the 



