17,5 Chilton: A New Amphipod 517 
the same, and the third uropod when fully developed about 5.5 
millimeters. 
In the upper antenne the first and second joints of the pedun- 
cle are of about equal length, the first pair bearing at the end 
a distinct setule on the lower margin, and a few finer setules 
at the end of the second joint. The third joint is about one- 
third the length of the first. The flagellum is greatly elongated, 
sometimes containing as many as thirty-six joints, as shown in 
Plate 1, fig. 1; in this specimen the antenna on the other side 
was shorter and contained only twenty-eight joints. The acces- 
sory appendage is minute, consisting of two very small joints, 
and is easily overlooked. It will be seen from this description 
that the first antenna differs considerably from that of N. chil- 
kensis in which the second joint of the peduncle is greatly elon- 
gated and bears distinct tufts of sete on the upper margin 
toward its extremity. In the second antenna the gland cone is 
distinct, the last two joints of the peduncle subequal in length, 
the flagellum consisting of six distinct joints, the first much 
longer than any of the others, being nearly as long as the rest 
of the flagellum. In N. chilkensis the joints of the flagellum 
are faced together. 
The upper lip is regularly rounded and slightly more convex 
near the median line where it is covered in the usual manner 
by a fur of minute sete. 
In the mandible the first joint of the palp is rather elongated, 
about one-third that of the second which is somewhat curved 
and slightly broadened, the third joint is about as long as the 
second and bears toward the extremity a number of sete fully 
as long as the joint itself and extending almost at right angles 
to it. The cutting edges are normal and do not call for special 
description; the spine row contains numerous plumose spines. 
There seems to be little difference between the right and left 
mandibles. 
The lower lip is of the usual shape, the mandibular process on 
each side being well marked and with the extremity rounded; 
the inner lobes are distinct, but rather small. 
The first maxilla has the inner lobe well developed, broad, its 
oblique apical margin bearing twelve or more plumose setules; 
the outer lobe is of the usual shape, bearing about nine dentic- 
ulate setules; the palp appears to be the same on both sides 
and bears at the apex some stout setules and a few slender 
hairs. 
