igiS,] R. B. S. Sewell : New species of Copepoda. ii 



The anterior end of the head presents a uniformly rounded 

 ''forehead" and the rostrum is absent. The posterior thoracic 

 margin is rounded and unarmed. The abdomen consists of three 

 segments, of which the 3rd is extremely short, so short that it gives 

 the appearance of a two-jointed abdomen. The f ureal rami are not 

 symmetrical, that on the right side being the longer 



The abdominal segments and furca have the following relative 

 lengths : — 



35 : 41 : 5 : 19 = 100. 



The genital swelling forms a well-marked projection on the 

 ventral aspect of the ist abdominal segment. The 2nd furcal seta 

 is stouter and considerably longer than the rest ; the 5th seta 

 arises from the external margin, at the junction of the middle and 

 distal thirds of the segment, and there is a well-developed acces- 

 sory dorsal seta. 



The 1st antenna when folded back reaches to the middle of the 

 2nd abdominal segment. As in other members both of this genus 

 and of the genus Acartia, the proximal segments of the antenna 

 tend to become fused together : as the line of demarcation between 

 segments frequently runs in a spiral round the antenna, the least 

 change in position gives a totally different length measurement for 

 any given joint. So far as I can make them out the following 

 are the proportional lengths of the various segments in this 

 species : — 



Segments i : 2-4 : 5-6 : 7 : 8-9 : 10 : n : 12 : 13 -14 : 15 : 16 : 17 : 18 : 19 ; 20 : 

 53 : 120 : 37 : 42 : so : 32 : 24 : 26 : 66 : 37 : 79 : 55 : 55 = 63 : 50 : 

 21 : 22 : 23 : 24 : 35. 



53 : 40 : 55 : 42 : 21 = 1000. 



Segments 2 to 4, 5 and 6, 8 and 9 and 13-14 appear to be 

 fused together and segment 15 is also partially fused with the 

 preceding segment. Many of the segments bear oblique rows of 

 fine hair-like spines on their posterior surface. 



The 2nd antenna has the same peculiar form as in ^. tortani- 

 formis [vide Sewell, 1912, p. 347 and pi. xxi, fig. 4). 



The mandible bears four teeth of which the ist is separated by 

 an interval from the remaining three as in ^. tortaniformis. 



The maxilliped very closely resembles that of A. tortaniformis : 

 the end joint bears the same four spinous processes, but the basal 

 segment is armed with a row of 10-12 small spines instead of four 

 large ones. 



The 1st pair of legs. — Bach consists of a two-jointed basal 

 portion, a three- jointed exopod and a two-jointed endopod. Ex- 

 opod I and 2 are devoid of marginal spines ; exopod 3 bears 

 one long seta-like marginal spine and the usual end-spine. On the 

 inner margins the segments of the exopod bear i, i, and 5 setae 

 respectively. 



The 2nd pair of legs. — The exopod is three- jointed; exopod i 

 bears a small marginal spine and one internal seta ; exopod 2 has 

 no marginal spine but bears one internal seta ; exopod 3 bears a 



