820 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
The segments of the thorax are equal in length. The epimera of the second, third, and fourth 
segments are not produced posteriorly beyond the margin of the segment; those of the fifth, sixth, 
and seventh segments are produced backward. 
There is an arcuate carina on all the epimera which extends from the post-lateral external angle 
to the internal antero-lateral angle of the opposite side. 
All 6 segments of abdomen distinct, the first segment a little shorter than the 4 following. The 
sixth or terminal segment is well rounded posteriorly, with a pronounced and wide emargination, 
quadrangular in shape, in the median line. On either side of this emargination the posterior margin 
is crenulate for some distance and provided with minute spines, about 8 on either side. 
The uropoda (fig. 1 e) are about equal in length and are not longer than the terminal abdominal 
segment. The outer branch is oval in shape, denticulate, and provided with spines on the external 
and posterior margin. The inner branch is unlike the outer branch in shape, and tapers to a narrow 
extremity at the post-lateral side of the external margin, the external margin being almost straight; 
this branch is more distinctly crenulate on the lower part of the external margin and provided with 
small spines. 
Fig. 1 .— JEga quadratasinus. (a) General figure, x 4; (6) Frontal lamina and peduncles of both pairs of antennae, x 7; 
(c) Terminal segment and uropoda, x 8; (d) Leg of 3d pair, x 8. 
The first three pairs of legs are prehensile. On the third pair (fig. 1 d) there is 1 spine on the 
ischium, 6 on the merus, 2 on the carpus, and 1 at the distal end of the propodus. The 4 following 
pairs of legs are gressorial, and are provided with spines on the ischium, merus, carpus, and propodus. 
Only one specimen was obtained in 1902 from Kauai Island, the Hawaiian Islands, by the United 
States Fish Commission steamer Albatross. 
Type in United States National Museum. Cat. No. 28971. 
This species approximates more closely to JEga incisa a Schioedte & Meinert than to any other 
described species of the genus. It differs, however, in the shape of the abdomen, which is more 
triangular in A. incisa; in the shape of the terminal notch, which is V-shaped in A. incisa, more quad- 
rangular in A. quadratasinus; in the smaller eyes, which do not meet in the median line as in A. incisa 
but are separated by a space equal to the length of one eye; by the longer antennae of both pairs, each 
containing also a greater number of joints in the flagellum; and in having the prehensile legs provided 
with numerous spines, while in A. incisa there is a single spine on the ischium and a single one on 
the carpus. 
aNaturhistOrisk Tidsskrift (3), xn, 1879-1880, pp. 373-374, pi. x, figs. 13-15. 
