510 
surface in area of lateral seta; in an individual, 
this dorsal ornamentation may be present on 
one ramus but not on the other. Inner margin 
with long hairs. Terminal inner setae longer 
than caudal rami (about 70:58). 
Left antennule with setation typical, differ- 
ing from that of female in having 1 seta on 
segment 11, and in having aesthetes on all of 
segments 1-19, except on segment 4; aesthetes 
also considerably longer, as in yukonensis. 
Right antennule with segments 12-16 very 
swollen. Segments 8-12 with spines, all of 
which are shorter than width of segments; 
those of 9 and 12 only a little longer than the 
others. Terminal segments armed as m yukon- 
ensis. Apical segment only a little longer than 
the preceding. 
Mandible as in female. 
Leg 5 (Fig. la) having left basal portion 
wider than right and with an inner protrusion. 
Right second basal segment enlarged, its 
greatest width to length 20:30, without 
marked inner protrusion. Right exopod 2- 
segmented, first segment only a little longer 
than basipod 2, but much narrower. Terminal 
segment longer than exopod 1, 47:35; inner 
basal portion without a conspicuous swollen 
portion; terminal part with cuticle of both 
margins irregular. Left leg having second basal 
segment shorter than that of right side, with- 
out marked inner protrusion. Exopod 2-seg- 
mented, both segments with a stout outer 
spine; terminal segment longer than the first, 
45:30. Apical portion of segment 2 broad- 
ened, outer part extended as a swollen, round- 
ed digit, tipped with small seta; inner portion 
having cuticle crenate, anterior side with pad 
of thickly set fine hairs which protrude be- 
yond margin. 
COMPARISON OF ASIATIC AND ALASKAN 
FORMS 
Eurytemora composita has been known 
only from the type locality. Lake Issyk-Kul, 
a large, brackish lake in western Turkestan. 
Some of Reiser’s specimens were examined 
by Smirnov, who supplemented the descrip- 
PACIFIC SCIENCE, Vol. VII, October, 1953 
tion of the type material, giving a more exact 
illustration of the male fifth leg. Since the 
two descriptions otherwise agree very well, 
it may be assumed that the Asiatic form is 
well enough known to compare it with the 
Alaskan form with some degree of certainty. 
The details of the antennules and mandible 
are not known for the typical form. 
The Asiatic and Alaskan females exhibit 
the following similarities, all of which are 
diagnostic characters of the species: 
Size— 1.2-1. 4 mm. 
Metasomal wings produced, with inner 
lobes. 
Genital segment with lateral hairs, con- 
stricted medially, with prominent, symme- 
trical, proximal lobes. 
Genital operculum rounded distally, recep- 
tacula located above medial sclerotization. 
Anal segment and caudal rami with dorsal 
ornamentation. 
Caudal rami subequal to segments 2 and 3 
(or a little longer), length 6 X their width. 
Shape and relative proportions of segments 
and spines of leg 5. 
Presence of inner setae on exopod 2 of leg 5 . 
The Alaskan female differs from the typical 
form in: 
Presence of dorsal ornamentation on second 
segment of urosome. 
Possible greater development of genital 
operculum. 
Leg 5 — Upcurved tip of inner process of 
exopod 1 and presence of two slender hair- 
like setae rather than a single stout seta on 
inner margin of exopod 2. 
No illustration of the male urosome has 
been given for typical composita, but Keiser 
states that the length of the rami is 7 X their 
width, and that hairs are present only on the 
inner margin. The Alaskan specimens differ 
in having the length of the rami about 10 X 
their width, and in the presence of hairs on the 
anal segment and on both margins of the 
rami. The fifth leg appears to be very similar 
in the proportions of the segments and the 
structure of the apical part of the left leg. 
