metasomal segment as well as the fourth and 

 fifth metasomal segments are fused (fig. 17). 

 The forehead is smoothly rounded and has a 

 strong rostrum (fig. 18). The posterolateral 

 margins of the metasome are rounded (fig. 19) . 



The urosome consists of 5 free segments and 

 the caudal rami which have the following pro- 

 portional lengths, from anterior to posterior: 

 23:22:18:19:6:12. The last segment is almost 

 completely telescoped into the fourth segment. 

 The caudal rami are as long as they are wide. 

 The distal margins of the second to fourth seg- 

 ments are each fringed by a row of small tri- 

 angular spinules. 



The uniramous left fifth leg (fig. 20) con- 

 sists of 5 segments, the third of which reaches 

 as far as the distal end of the basis of the right 

 leg. The distal segment is small and inserted a 

 short distance before the end of the fourth seg- 

 ment; the two segments together thus form a 

 chela (figs. 21 and 22). Distally on the last seg- 

 ment are 2 teeth, which are curved outward. 

 The right fifth leg consists of a well-developed, 

 2-segmented basipod, a 2-segmented exopod, 

 and a 1-segmented endopod. The first exopodal 

 segment bears 4 triangular processes along the 

 internal margin — 3 on the proximal half, and 

 1 near the distal end of the margin. The distal 

 segment has a triangular process along the in- 

 ternal margin, at about one-third the length 

 from the proximal end, and a row of small 

 teeth distal to the process. The endopod is S- 

 shaped and has 3 triangular processes along 

 the external margin. 



Euchirella nnvipina, new species 

 (Plate 6, figs. 1-21; plate 7, figs. 1-11) 



Occurrence 



Sta. 3. 6 adult females, 4.28 to 4.56 mm. 

 Sta. 5. 7 adult females, 4.60 to 4.70 mm. ; 



1 adult male, 3.84 mm. 

 Sta. 7. 3 adult females, 4.70 to 4.80 mm. ; 



1 adult male, 3.93 mm. 

 Sta. 9. 3 adult females, 4.60 to 4.89 mm. ; 



3 adult males, 3.93 to 4.03 mm. 



Description of Female 



The total length is from 4.28 to 4.89 mm. 

 The prosome is about 4.3 times longer than the 

 urosome. The first metasomal segment is fused 

 with the cephalosome, but a line of demarca- 



tion is often visible in stained specimens. The 

 fourth and fifth metasomal segments are com- 

 pletely fused. The forehead in dorsal aspect 

 (plate 6, fig. 1) is slightly triangular and in 

 lateral aspect (plate 6, fig. 2) smoothly curved 

 into a powerful rostrum. The rostrum is single, 

 points forward, and has an acute apex. The 

 base of the rostrum has a distinct constriction 

 from which 2 sensory hairs arise. 



The posterolateral margins of the metasome 

 are rounded. The urosome (plate 6, figs. 3-5) is 

 4-segmented ; the segments and the caudal rami 

 have the following proportional lengths, from 

 anterior to posterior: 51:12:12:11:14. The 

 genital segment is about as long as it is wide 

 and slightly asymmetrical in dorsal aspect, as 

 it is produced distally on the left side. The 

 caudal rami are wider than long (24:19) and 

 have 4 strong, subequal terminal setae, a short, 

 strong external seta, and a curved internal seta. 



The 24-segmented antennule reaches the end 

 of the caudal ramus when folded back. The 

 arrangement of the various setae and the aes- 

 thetes is illustrated in plate 6, figure 6. 



The antenna (plate 6, fig. 7) has a short 

 endopod, about equal to the first 2 exopodal 

 segments combined. The first endopodal seg- 

 ment has 1 seta near the distal end of the in- 

 ternal margin, and the second endopodal seg- 

 ment has 8 setae on the internal and 6 -f 1 

 setae on the external lobe. The exopod is 7- 

 segmented; the proximal segment is produced 

 into a triangular process near the distal end 

 of the internal margin. Each of the 4 interme- 

 diate segments has 1 strong, plumose seta, and 

 the elongate distal .segment has 3 apical setae. 



The cutting edge of the mandibular blade 

 (plate 6, fig. 8) is armed with five groups of 

 strong teeth and 2 basal spines. The posterior 

 surface of the basis has a small process. The 

 endopod is 2-segmented ; the fir.st segment lacks 

 setae, but the second segment bears 9 apical 

 setae. The exopod is 5-segmented, the segments 

 together having 6 setae. 



In the maxillule (plate 6, fig. 9), the first 

 inner lobe is elongate, and has 12 .strong spines 

 plus 1 small spine. The second and third inner 

 lobes are well developed ; the second has 4 setae 

 of subequal length and the third 1 large plus 

 2 small .setae. The first outer lobe is low and 

 has 8 .setae. The basis is elongate and has 1 



546 



U.S. FISH AND WILDLIFE SERVICE 



