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; Euphyllopoda | G19 



with these is mainly produced by the foliaceous legs and less by the second pair 
J _ of antennae, while the development of the long tail [abdGnieay enables ean to 
m make sudden twists and jerks, like the adults. 
wr The above notes on the habits of the larvae were made partly by observing 
them in the pond, and partly by keeping them alive in a glass with water. I 
kept them for a month, but during that period they did not attain the size of 
those left in the pond, probably because they did not have the same food supply 
as in their natural surroundings. Thus more larvae were collected in the same 
pond on July 10-11, 1914; they now measured from about 5 to 10 mm. in length, 
and there were none younger than my stage V, described on p. 53. I kept ten 
of them, and it could now be decided, that the three largest of these were females 
and the rest males. The former had a short ovisac, the latter small claspers 
(second pair of antennae). There were still a great number of larvae in the pond; 
and they seemed to be thriving well, in spite of the fact that parts of the pond 
were completely dried up; even places with only a gallon of water were teeming 
with them. 
A smaller waterhole (remnant of a dried up lagoon-pond) nearby and on 
the same level (old beach) had a water temperature of 58° F. at 6 p.m. on July 
11. It contained, in spite of its small size, hundreds of Branchinecta paludosa 
larvae of the same size (5-10 mm.) as the ones mentioned above. : 
The four Branchinecta paludosa collected by Mr. D. Jenness in a pond 
on Barter island, Alaska were from 15 to 20 mm. long, and represented 
three males and one female, all mature and of the same appearance as those next 
to be described. 
The specimens from Martin point, Alaska, July 26, 1914, measured from 
15 to 20 mm., the full grown males being a little bigger than the corresponding 
females. The movements of the animals were very swift, twistings of the body, 
somersaults and jerking jumps abounding, particularly with the females when 
I tried to catch them. I give here an outline (text figure 4a-c) of the head and 
genitalia of one of the mature males, and of the second antennae of one of the 
females, all side-views. The row of hooked spines or teeth on the inner side of 
the basal segment of second antennae, the long, distal part of the latter, and the 
terminal spines and short filament on the genitalia of the male are easily seen; 
also the contractile nature of the second antennae of the female. In colour the 
males were when alive, transparent, pale white-green, with the three eyes black, 
while the foliaceous legs, brain-part and front-edge of the large claspers (2nd pair 
of antennae) were dark green, the intestinal canal pink (copepod-content?), 
and the ripe semen-thread white. 20 males were kept. 
The females were much more brightly coloured, a fact also known from 
other fairy-shrimps (for instance Eubranchipus gelidus). They had a trans- 
parent, whitish-pink main colour with black eyes. Front part of head (from 
between the eyes) with its appendages, the back (dorsal side) and sides (from 
above the beginning of the foliaceous legs to the last abdominal segment and the 
base of the foliaceous legs dark purple. The tail (abdomen) behind the ovisac 
of a dark blue-violet colour, with a white stripe (unripe egges?) on each side 
underlying the violet colour of the tail and the purple colour of the back, 
stretching from behind the base of the ovisac to the middle of the series of 
foliaceous legs. Eggs in uterus ripe, 1-5 mm. in diameter of a red-brown colour. 
Ovisac and intestine paler; unripe eggs in ovisac as a rose streak on both sides 
of the ripe ones. There was some variation in the distribution and intensity 
of these purple and violet colours among the 21 females I secured here, but 
the dark-purple, streak on the dorsal side of the intestine is particularly constant 
and very characteristic of the mature female of this species (see p. 23). 
In several of the ponds on Herschel island I secured on August 13-14, 1914, 
four mature males (22 cm.) and three mature females (23 cm.) of Branchinecta 
paludosa, the biggest specimens of this species I saw during the expedition. 
26549—3 
