HANSEN: THE ISOPODA. 105 
Color. The dorsal surface is light yellowish gray with a faint purple tone 
on a part of the three anterior thoracic segments, and the last abdominal seg- 
ment yellowish white; the eyes dark grayish, almost black. 
Size. The single specimen is 31 mm. long, 16.2 mm. broad. 
Habitat. Station 3403 (Lat. 0° 58’ 30” 8., Long. 89° 17’ W.), 384 fathoms, 
1 specimen. 
Remarks. The species is very closely allied to Æ. psora (L.), but is distin- 
guished especially by smaller eyes, longer antennule, and the last abdominal 
segment being posteriorly more produced. From Æ. maxima it is distinguished 
especially by longer antennule, and by a different shape of the last abdominal 
segment and of the uropods. 
5. Aga plebeia, n. sp. 
Plato II. Fig. 4-4 d. 
Six specimens, one male and five females, three of the latter with well 
developed marsupium. 
Head. The frontal margin with the sub-median curves rather indistinct ; the 
median process extends a little below the inferior edge of the antennule, its 
apex almost or quite reaching the frontal plate. The frontal plate about twice 
as broad as long and strongly compressed, forming a high tranverse keel, which, 
seen from in front, shows the shape of the half of an oval. The eyes (Fig. 4) 
are very large ; the distance between them considerably shorter than the breadth 
of the frontal process. 
Antennule. Much longer than the peduncle of the antenn® (Fig. 4), and 
bent backwards, reaching almost to or even beyond the posterior angle of the 
first thoracic segment. The peduncle is somewhat shorter than the flagellum, 
and almost attains the distal end of the penultimate joint of the peduncle of 
the antenne; the first joint is about as long as broad, with the antero-interior 
angle broadly rounded; the third joint of the peduncle as long as, or a little 
longer than, the two proximal joints together. The flagellum with twenty-one 
to twenty-three joints. 
Antenne. They reach a little beyond the posterior margin of the second, or 
almost to the posterior margin of the third thoracic segment. The flagellum 
14 or 14 times longer than the peduncle, with seventeen or eighteen joints. 
Thorax (Fig. 4a). The postero-lateral angle of the first segment rectangular 
or a little acute, that of the epimera of the second and generally of the third 
segment conspicuously produced and acute; the angle of the fifth and sixth 
epimera almost or quite rectangular. The epimera of the seventh segment 
somewhat produced and acute. 
Thoracic Legs. The three anterior pairs slender and rather long: the fourth 
joint not incrassated, with concave interior margin (Fig. 4 b), and with a couple 
of small spines at the distal inner angle; the sixth joint rather long, with a 
strong spine on the interior margin near the end; the claw very long, and 
