the following proportional lengths, from an- 

 terior to posterior: 28:20:16:36. 



The genital segment is symmetrical, wider 

 than long, and has dorsally a row of small 

 spinules along its distal margin. The second 

 urosomal segment has ventrally a knoblike pro- 

 jection and dorsally 2 rows of small spinules 

 along the distal border. The caudal rami are 

 symmetrical and about 3.5 times as long as 

 wide. 



The antennule is 24-segmented ; the last 5 

 segments extend beyond the end of the caudal 

 ramus. The endopod of the antenna (plate 9, 

 fig. 16) is short — about one-half the length of 

 the exopod. The second endopodal segment has 

 8 + 1 setae on the internal lobe and 6 + 1 

 setae on the external lobe. 



The mandibular palp (plate 9, fig. 17) has a 

 triangular basis, which has a seta on the pos- 

 terior surface. The exopod is 5-segmented; each 

 of the first to fourth segments has 1 seta, and 

 the terminal segment 2 setae. The endopod is 

 small ; the first segment has 2 setae, and the 

 second segment 7 setae. The mandibular blade 

 (plate 9, fig. 18) consists of a lai-ge separate 

 tooth and a plate with about 7 acute teeth. 



The maxillule is relatively small; details of 

 its structure are shown in plate 9, figure 19. 



The maxilla (plate 9, fig. 20) is well de- 

 veloped. The first to fourth lobes each bear 

 2+1 spinose setae. The fifth lobe is much better 

 developed ; it has 1 long spinose seta and 2 

 small spiniform setae. The endopod has 5 long 

 spinose setae, 1 short spinose seta, and a small 

 spiniform seta. 



The coxa of the maxilliped (plate 9, fig. 21) 

 is stout and has 3 well-developed lobes. The fir.st 

 lobe has 1 spinose seta plus 1 spiniform seta, 

 the second lobe 2 spinose setae plus 1 spiniform 

 seta, and the third lobe 3 small spiniform setae. 

 The basis is about as long as the coxa and 

 carries 3 setae distally. The endopod is also 

 as long as the coxa and is 5-segmented. 



The basipod of the first leg (plate 9, fig. 22) 

 is stout and has an internal seta on each seg- 

 ment. The endopod is 3-segmented and shorter 

 than the first and second exopodal segments 

 combined. The first segment has 1 internal seta; 

 the second segment, 2 internal setae; and the 

 third segment, 3 internal setae, 1 external seta, 

 and 2 terminal setae. The exopod is also 3- 



segmented; it has 1 + 1 + 2 external spines, 



1 + 1 + 4 internal setae, and 1 terminal spine. 

 The second and third pairs of legs (plate 9, 



figs. 23 and 24) are similar. On the basipod, 

 only the coxa has an internal seta. The endopod 

 is 3-segmented and extends slightly beyond the 

 distal border of the second exopodal segment. 

 The segments have 1, 2, and 8 setae, respec- 

 tively. The exopod is also 3-segmented ; the 

 first and second segments each have 1 external 

 spine and 1 internal seta. The third segment 

 has 3 external spines, 5 internal setae, and 1 

 terminal spine. 



The fourth leg (plate 9, fig. 25) differs from 

 the third leg only in the number of setae on 

 the third endopodal segment — it has 7 setae in- 

 stead of 8. 



The basipod of the fifth leg has no setae 

 (plate 9, fig. 26). The exopod is 3-segmented. 

 The first segment has 1 external spine and a 

 round projection along the internal margin. 

 The second segment has 1 external spine and a 

 strong spiniform projection from the internal 

 margin. This projection is shorter than the 

 third exopodal segment and has distally a row 

 of stiff" hairs along the internal margin. The 

 third exopodal segment has 2 external spines, 

 4 internal setae, and a terminal spine. The 

 endopod is also 3-segmented ; it has 1 seta on 

 the first segment, 1 on the second, and 6 on the 

 third. 



Description of Male 



The total length ranges from 1.84 to 2.04 mm. 

 The proportional lengths of the prosome and 

 urosome are 2.8:1. The first metasomal seg- 

 ment is incompletely separated from the ceph- 

 alosome; a line of separation is visible only on 

 the dorsal side. The posterolateral corners of 

 the metasome are smoothly rounded (plate 10, 

 fig. 1 ) . The urosome is 5-segmented ; the seg- 

 ments and the caudal rami have the following 

 proportional lengths, from anterior to poste- 

 rior: 15:17:17:5:14:32. The caudal rami are 

 about 3 times as long as wide. 



The left antennule is 24-segmented ; the last 



2 segments extend beyond the end of the caudal 

 ramus. The right antennule (plate 10, figs. 2 

 and 3) is modified for grasping the female. The 

 external margins of the 17th to 19th segments 

 are each fringed with a row of acute teeth. 



CALANOID COPEPODS FROM NORTH PACIFIC 



559 



