420 
CHI YOMATSU ISHIKAWA. 
supported upon very short stalks. The abdomeu consists of 
but six segments, the telson being still united with the last. 
The broad triangular fin (fig. 86) is furnished with fourteen 
long setae, each of which is finely feathered on both sides, 
except the two outermost pairs, which are feathered only on 
the inner side. The three inner pairs of the long setae are, 
moreover, provided with short spines on both sides. The 
spaces between the long setae are furnished with short setae 
( iV°)- Within the abdominal segments, from the first to the 
fifth, are seen ganglia (fig. 85, n .) of the ventral nerve-cord, 
united by double commissures. The first, second, and the 
third ganglia are large, and spherical in form, while the two 
succeeding ones are small. The anus is seen as a longitudinal 
slit on the lower side of the telson. 
The first pair of antennae (fig. 85. At. 1) consists of a basal 
segment, and a short distal one, which carries four setae, two 
of which are the modified sensory organs. The outer two 
are of unequal length, the shorter being feathered on both 
sides. The proximal segment carries a single, long, large seta 
on its distal end. 
The second pair of antennae (fig. 85, At. 2) is nearly of the 
same length as the first pair. It consists of a short distal 
segment, with two proximal branches, the outer of which (the 
future flagellum) is large, and furnished with thirteen setae on 
its distal margin. The inner branch is slender, and furnished 
with two setae of unequal length, the longer of which is 
feathered on both sides. The shorter is curved, and bears a 
small, bud-like appendage on its inner side near the base. 
There is also a short, stout spine at the base of the inner branch 
on the distal end of the proximal segment of it. 
The green gland (fig. 85, gg., figs. 93 and 94) is situated at 
the base of the proximal segment, its opening being perched 
on a little eminence on the inner side of the segment. 
The labrum (fig. 85, lb.) is large, lying slightly posterior to 
the second pair of antennae. 
The mandible (fig. 84, md .) consists of two branches, the 
anterior of which is furnished with numerous teeth, and the 
