large and 2 small setae at the inner apex. The 

 endopod and the exopod are small and 1-seg- 

 mented, and have 5 and 11 setae, respectively. 



The maxilla (plate 6, fig. 10) is short and 

 has 5 prominent lobes. Each of the first to 

 fourth lobes has a transverse row of small 

 spinules on the posterior surface. The first lobe 

 has in addition 3 long spinulose setae and 1 

 short, spinulose seta ; the second and third 

 lobes each have 2 long spinulose setae and one 

 short spinulose seta ; and each of the fourth and 

 fifth lobes has one strong, dagger-shaped spine, 

 1 long spinulose seta, and 1 short spinulose 

 seta. The endopod seems to be 4-segmented. 

 Each of the first 3 segments has 1 spinulose 

 seta. These setae are about equally long. The 

 terminal segment has 3 short setae. In addition, 

 the second and third segments each have a tiny 

 seta. 



The maxilliped (plate 6, fig. 11) has a 

 slender basipod, and a short endopod that is 

 about one-half the length of the basis. The coxa 

 has four groups of setae, composed of 1, 2, 3, 

 and 3 setae, respectively. Some scattered spin- 

 ules are at the insertions of the setae of the 

 last group. The basis has 3 setae at the middle 

 and 2 setae at the distal end of the internal 

 margin, in addition to a row of spinules along 

 the proximal portion of the same margin. The 

 endopod consists of 5 segments which have 4, 

 3, 3, 3 + 1, and 4 setae, respectively. 



The first pair of legs (plate 6, fig. 12) has 

 2-segmented exopods and 1-segmented endo- 

 pods. The basipod is fringed with hairs along 

 the internal margin and has a seta at the 

 distal end of the same margin. The endopod is 

 slightly shorter than the first exppodal seg- 

 ment, and its external margin has a round 

 tubercle that bears a transverse row of spin- 

 ules on the anterior surface. The endopod has 

 3 internal setae and 2 apical setae. The first 

 exopodal segment has 1 internal seta and 2 

 subequal external spines. The second exopodal 

 segment has 1 strong external spine, 3 internal 

 setae, and 1 long apical spine. 



In the basipod of the second leg (plate 6, 

 fig. 13), the coxa is fringed with hairs only 

 along the internal margin and has an internal 

 seta. The endopod is a single segment (a line 

 of fusion is visible in stained specimens) that 

 is slightly shorter than the combined length of 



the first and second exopodal segments. The 

 endopod has 3 internal setae, 1 external seta, 

 and 2 apical setae. The first and second exop- 

 odal segments each have 1 internal seta and 1 

 strong external spine. The third exopodal seg- 

 ment is longer than the first and second seg- 

 ments combined and has 3 strong external 

 spines, 4 internal setae, and 1 long terminal 

 spine that is armed with a row of acute teeth 

 along the external margin. 



The third leg (plate 6, fig. 14) is slightly 

 larger than the second, but its basipod and exo- 

 pod are similar in anatomical details to those 

 of the second. The endopod is 3-segmented ; the 

 segments have 1, 1, and 5 setae, respectively. 

 There are 2 triangular, flattened processes 

 along the external margin of the first endop- 

 odal segment. 



The fourth leg (plate 6, fig. 15) is slightly 

 smaller than the third, and its coxa has a 

 strong spine in addition to a stout internal 

 seta. The spine extends beyond the distal end of 

 the segment. Furthermore, the posterior sur- 

 face of the coxa has 4 delicate setae, one of 

 which is immediately distal to the insertion of 

 the spine. Two such setae are also on the pos- 

 terior surface of the basis. The exopod and 

 endopod are anatomically similar to those of 

 the third leg. The fifth pair of legs is absent. 



Description of Male 



The total length ranges from 3.84 to 4.03 mm. 

 The proportional length of the prosome to the 

 urosome is about 3.7:1. The prosome is more 

 slender than in the female and has a low tri- 

 angular forehead in dorsal aspect (plate 6, fig. 

 16). In lateral view the forehead is smoothly 

 rounded into a strong rostrum and devoid of 

 crests (plate 6, fig. 18). The cephalosome and 

 the first metasomal segment, as well as the 

 fourth and fifth metasomal segments, are com- 

 pletely fused, as they are in the female. The 

 posterolateral margins of the metasome are 

 rounded. 



The urosome (plate 6, fig. 19) consists of 5 

 free segments and the caudal rami. The seg- 

 ments and the caudal rami have the following 

 proportional lengths, from anterior to poste- 

 rior: 25:24:17:19:6:9. The distal margins of 

 the second to fourth urosomal segments are 

 each fringed with a row of small spinules. 



CALANOID COPEPODS FROM NORTH PACIFIC 



549 



