4i8 
ZOOLOGY OF THE FAR EAST. 
The mouth parts present no special points of distinction. They agree essentially 
with those of C. stygia, as figured by Packard. 
I give herewith figures of the maxillipede, second, third and eighth thoracic limbs 
(PI. XV, figs. 12-15) of the male, which will .serve to denote the details of these 
appendages. The second thoracic limbs are prehensile with the propodal joint 
dilated and armed with two spines on the proximal part of the palmar margin. 
They differ from those of C. stygia, in having the propodus less dilated and without 
triangular processes. In this character they approach C. richanisonae , Hay, and 
C. smithsii, Ulrich. There is very little difference between the sexes in the form of 
the second pair of thoracic limbs, those in the female being of essentially the same 
form as those in the male but slightly smaller. 
The first pleopod of the male (PI. XV, fig. 16) has the sympod armed with four 
coupling hooks. The ramus consists of a broadly oval plate, twice as long as broad 
and furnished with .setae on the outer and posterior margins, the inner margin being 
unarmed. 
The second pleopod of the male (PL XV, fig. 17) differs from the same appendage 
in C. stygia in having a long curved process from the basal joint of the endopod 
which turns inward along the inner margin of the sympod. The whole appendage is, 
in fact, curiously like the same appendage in Asellus aquaticus. 
The third pair of pleopods of the male (PI. XV, fig. 18) consist of a short sympod, 
an oval uni-jointed endopod and a very large two-jointed exopod having the 
posterior margin truncate and armed with a few plumose setae. 
The fourth and fifth pairs of pleopods of the male consi.st of a short sympod and 
two rami, the endopod unjoin ted, the exopod slightly larger than the endopod and 
two-jointed. 
The uropods in the male are longer than the pleon, basal joint long and narrow 
equal to. half the length of the appendages, endopod equal in length to the basal 
joint but narrower and terminated by a tuft of setae, exopod about half the length 
of the endopod and still narrower, also terminated b)'- a tuft of setae. 
In the female the uropods are slightly shorter than the pleon and the exopod is 
about two-thirds of the length of the endopod. I am unable to say whether this 
apparent sexual difference is constant, because there is only one female in the 
collection. The uropods of Asellidae are very easily broken off and it is difficult to 
distinguish regenerated appendages from those which have had a normal growth 
without injury. 
This species is distinguished at once from all the other species of the genus by 
the presence of distinct though very small eyes. In this respect it is the m.ost 
primitive species of the genus. It may also be distinguished by the relatively 
shorter antennae, the form of the second thoracic limbs and especially by the form 
of the first pleopod of the male. The latter is curiously similar to the same appen- 
dage in Asellus aquaticus, which is considered to be the most primitive of the 
species of Asellus, and C. kawamurai is, I think, the most primitive of the species 
of Caecidothea. 
