COPEPODS OF THE WOODS HOLE REGION 473 



1-segmented, with two apical setae longer than the segment; second 

 maxilla 2-segmented, the second segment fringed with spiny teeth 

 along its outer margin, the terminal claw fringed with minute hairs. 

 Maxillipeds greatly enlarged, the basal segments completely fused 

 and turned downward and forward along the midline, and reach- 

 ing far in front of the carapace. They are separated at the tips 

 and each ends in a simple claw, which is folded back dorsally onto 

 the segment. They thus work vertically like those of Eudactylma 

 but are radically different in structure. 



Kami of the first four pairs of legs subequal in length, 3-segmented, 

 armed in the first legs with setae, in the other pairs with spines only ; 

 the exopods have stout spines on the outer margins of each segment. 

 In the first legs the two basal endopod segments carry a spine at the 

 outer distal corner, the end segment carries a single apical seta. In 

 the second and third legs the basal endopod segment has a single 

 spine, the second segment has two spines close together, the end seg- 

 ment has a long apical and a short outer spine. In the fourth legs 

 the basal segment has a row of spiny teeth along its outer margin, 

 the one at the distal corner enlarged, the second segment has a row 

 along its distal margin, and at the outer distal corner a group of 

 three, the end segment has a row around its distal end, the middle 

 spine much longer and stouter than the rest. The fifth legs are each 

 made up of a 1-segmented lamina without spines or setae. Total 

 length, 4.7 mm. Greatest width (second segment), 0.95 mm. 



Male. — Carapace elliptical, evenly rounded anteriorly, without a 

 rostrum, and squarely truncated posteriorly; second segment a little 

 narrower than the carapace, third, fourth, and fifth segments dimin- 

 ishing rapidly, fifth segment only a fourth as long as the fourth seg- 

 ment, and much narrower, its sides strongly convex and armed with 

 the rudimentary fifth legs. Genital segment as wide as the fourth 

 segment and twice as long, with nearly straight sides and evenly 

 rounded corners. Abdomen 4-segmented, segments diminishing back- 

 ward, the anal segment fringed with spines along its posterior mar- 

 gin. Caudal rami as long as the anal segment, each tipped with three 

 plumose setae and two small spines. Antennae, mouth parts, and 

 legs similar to those of the female, except the maxillipeds ; these are 

 entirely separate and extend sidewise beyond the margin of the 

 carapace. Total length, 2 mm. Greatest width (carapace), 0.42 mm. 



Remarks. — This species may be identified by the peculiar maxilli- 

 peds of the female and in the male by the very short and narrow fifth 

 segment. The fact that it has been found both in the nostrils and on 

 the gills of its host is quite peculiar, since parasites from these two 

 localities usually differ greatly. 



