Mysidacea, Tanaidacea and Isopoda. 
413 
is about eleven times as long as broad, the terminal joint one-fifth of the total 
length and acutely pointed. 
The tarsus of the third to the fifth thoracic limbs is seven-jointed, of the sixth 
and seventh limbs six- jointed and of the last thoracic limb eight-jointed. The 
flagellum of the exopod is nine-jointed and the basal joint of the latter has a small 
spine on its outer distal corner. The lobes on the inner margin of the third and 
fourth joints of the endopod of the first thoracic limbs are well developed. 
The fourth pleopod of the male (PI. XV, fig. 4) is very long, reaching to the 
middle of the telson. The proximal joint of the outer ramus is twice as long as the 
distal joint which in its turn is one and a half times as long as the two terminal 
setiform processes. 
I have already alluded to the close relationship of this species to N. nigra and 
pointed out that it may be distinguished by the characters of the rostrum, eye 
and fourth pleopod of the male. 
It is, however, even more closely allied to Heteromysis intermedia, Czerniavsky, 
which is a true Neomysis, and Zimmer has suggested that the two species are probably 
synonymous. A fuller description of A^. intermedia is badly needed. Nakazawa 
has recorded the latter from Japan but has not offered any detailed description of 
his specimens. The only serious point in which it differs from N . awatschensis is in 
the form of the fourth pleopod of the male. Czerniavsky describes this appendage 
as having four joints in the exopod', the first and second of which are equal in length 
and each as long as the inner ramus, the third and fourth joints quite minute and 
sub-equal, and the two terminal setae short but longer than the combined third and 
fourth joints. His figure bears out this description, but I am bound to confess that 
the figure depicts an appendage which does not look to be fully formed and which 
belongs in reality to an immature male. Until this point is cleared up by an exami- 
nation of fully adult specimens it is impossible to regard the two species as 
synonymous. 
N . awatschensis is recorded from Kamtschatka by Brandt, Czerniavsky and 
Derzhavin. The latter author records it as abundant in the brackish water of the 
rivers of the Kamtschatka peninsula which drain the large series of relict lakes 
found there. Its habitat in Japan is of precisely the same nature. 
" There is an important fishery for these little Mysids in Kasumi-ga-ura, a 
lagoon of almost fresh water on the Pacific Coast of the Main Island of Japan. They 
are caught in a peculiar kind of large trawl, the bag of which is formed of very 
coarsely woven stuff. A^. A." 
Genus Anisomysis» Hansen, 1910. 
Anisomysis ijimai, Nakazawa. 
A. ijimai, Nakazawa, 1910, p. 252, pi. viii, figs. 5, 14. 27, 33. 
A. ijimai, Zimmer, 1915, p. 171. 
Locality : — Tateyama, mouth of Tokyo Bay, Japan, numerous specimens (pre- 
sented by Dr. Nakazawa). 
