Birge—Notes on Cladocera. 
1025 
largest. This seta is lost in nearly 80% of the specimens which 
I have seen, and one or both of the two other small ones are 
often gone, as well as the terminal joint of the larger ones. 
The feet, labrum, mandibles, and maxillae present nothing 
unusual in their structure. The sixth foot has a branchial 
sac. 
The posfabdomen (PI. LXVII, tigs. 3, 6) is in general con¬ 
ical. It bears 11-15 clusters of lancet-shaped spines, 2-5 in a 
cluster. If there are two or three they stand nearly parallel; 
if 4 or 5 they diverge. There are besides numerous clusters 
of tine hairs. The terminal claws are long, curved, with two 
long basal spines and a third, very small one, proximal to 
them; they are denticulate and have spinules on the convex 
side. The postabdomen has no median projection like that of 
P. szalayi. The abdominal setae are long, 2-jointed, plumose 
and borne on distinct, widely separated papillae. 
The shell gland (PI. LX VIII, fig. 1) has three loops, dorsal,, 
ventral, and posterior. The posterior loop is large and open, 
and of a form which might serve as a beginning to the extreme 
development found in Latonopsis australis. 
The intestine is straight, with a small median forward pro¬ 
jection. The eye is large, oval; it lies on the ventral side 
of the head, with a short optic nerve. The macula nigra is. 
small and oval. 
The color is yellowish, semi-transparent. The length of the' 
female isT.8-2.0 mm.; male, about 0.9 mm. 
The male resembles the young female. The antennul.es- 
(PI. LXVII, fig. 9) are very long, often two-thirds the length 
of the animal; curved; the fiagellum and base firmly united,, 
the former bearing a row of very fine setae along the distal 
half. There is a slender process on the base near the attach¬ 
ment to the head, extending toward the median plane. The 
copulatory organs (PL LXVII, fig. 5) are simple, long, cylindri¬ 
cal, as in Latona. The endopodite of the first foot is modified 
into a clasping apparatus, more complex than in any other oi 
the Sididae. The tip is bent over into a strong, curved, mov¬ 
able claw (PI. LXVII, figs. 7, 8) serrate on the inside. A lit¬ 
tle way distal from the attachment of the claw there is a large^ 
