102 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
the sixth abdominal segment, and especially of the uropods, furnish us with 
more distinguishing marks than are generally recognized, but as most of these 
details are more easily apprehended from figures, I will direct the attention of 
future students to these facts, believing that proportionally rather large and 
very accurate drawings of the parts mentioned will be extremely useful. 
In specimens of Æginæ taken on fishes, the ventral side of the thorax is 
often, nay almost generally, vaulted, and sometimes very considerably so, 
owing to the fact that the alimentary canal is greatly distended by blood 
sucked from the host ; another result of this swollen condition is that the seg- 
ments of the thorax very often become drawn out from each other. In speci- 
mens taken on the bottom of the sea by trawl or dredge, the ventral side is not 
vaulted, and the thoracic segments are not drawn out, it follows that such 
specimens ¢ .e comparatively shorter in proportion to their breadth than most 
of the specimens taken on fishes, and therefore present a somewhat different 
aspect. No specimen of the Æginæ in this collection has the ventral side 
vaulted, and all seem to be taken on the bottom. 
Schiódte and Meinert divide the species of the genus Æga into two groups. 
The first of them is thus diagnosed : “Scapi antennarum infra plani vel con- 
cavi, invicem accommodati. Lamina frontalis plana vel concava,” and to this 
group the two first described species, Æ. maxima, n. sp., and 4. acuminata, 
n. sp., must be referred. To the other group the two authors ascribe the fol- 
lowing characters: “Scapi antennarum teretiusculi vel compressi, invicem 
liberi. Lamina frontalis convexa vel compresse elevata,” and to this belong 
the two other species, Æ. plebeia, n. sp., and Æ. longicornis, n. sp. 
3. Æga maxima, n. sp. 
Plate II. Fig. 2-2 c0. 
Only one specimen, a female without marsupium. 
Head. The frontal margin rather concave on each side ; the median elon- 
gation acute, reaching to about the middle of the interior margin of the first joint 
of the antennule. The frontal plate “lamina frontalis” (on the ventral side of 
the head), about as long as broad, seen as much as possible from the side con- 
siderably convex, and seen from in front with a low and rather broad sublateral 
carina, and somewhat excavated in the middle. The eyes ovate, the shortest 
distance between them only a little less than the basal joints of both antennulx 
together. 
Antennule. Reaching very little beyond the end of the peduncle of the 
antenne, and a little beyond the anterior angle of the first thoracic segment. 
The peduncle very little longer than the flagellum; its basal joint as long as 
broad, with the upper side flatly convex, and the antero-interior angle rectan- 
gular. The flagellum 17-jointed. 
Antenne. Tach antenna, when bent backward, nearly attains the posterior 
margin of the second thoracic segment. The proportion between the peduncle 
and the flagellum is about that of 3 to 5; the flagellum 23-jointed. 
