Mysidacea, Taiiaidacea and Isopoda. 
417 
follows : — in the Japanese specimen the fifth thoracic limb was -8 of the length of 
the fourth and in the British specimen "85. 
These differences, therefore, are seen to be very slight and of little importance, 
and in view of Hilgendorf's positive statement that the pleopods of the male agree 
perfectly with those of European specimens, may be ignored. I think, therefore, 
that there is ver}^ little doubt that .4 . hilgendorfii should be relegated to the 
synonymy of i4 . aquaticus. This widely distributed species is now known to occur 
all over the Palaearctic regions of Europe and i\sia and is also found in N. America. 
" In Lake Biwa this species was taken in depths of from 180 to 260 feet and 
appeared to belong to the deep-water fauna, with the molluscs Pisidium casertanum 
(Poli), Valvata hiwaensis and V . annandalei , Preston, the leech Ancyrohdella biwae Oka 
and the Planarian Bdellocephala annandalei, Ijima and Kaburaki, with which it was 
taken in great abundance. Curiously enough, however, it was also taken in artificial 
concrete breeding tanks for fish at Hikone near the east side of the lake and, in very 
large numbers, in an ornamental stone basin containing only a few cubic feet of 
water and dead leaves in a temple-grove at the same place. A^. A." 
Genus Caecidothea, Packard. 
Caccidothea kawamurai, sp. nov. 
(PI. XV, figs. 11-18.) 
Locality : — From a well inside a house in the city of Otsu, Japan, 8. i. 1915, 
collected by Dr. T. Kawamura, three specimens, two males 16-17 mm., one female 
II mm. The well was a shallow one in which light panetrated to the bottom. 
Description : — Body (PI. XV, fig. 11) narrowly elongate in shape, seven times 
as long as broad, of even width throughout. 
Head nearly twice as broad as long, frontal margin slightly concave. 
Eyes present as a group of three ocelli on each side of the head, about the 
centre of the lateral margins. 
Thoracic segments more or less subequal in size, and quadrangular in shape ; 
each segment has an impressed line running across the segment at the anterior end ; 
in addition the first segment shows a V-shaped impressed line or groove ; lateral 
parts of the thoracic segments with a few short and scattered setae. 
Pleon about one quarter of the whole length of the body, one and three quarter 
times as long as broad, posterior margin slightly produced into an obtuse lobe between 
the bases of the uropods. 
First antennae short, not extending beyond the distal end of the fourth joint of 
the peduncle of the second antennae, peduncle equal in length to the first three 
joints of the peduncle of the second antennae, third joint the longest and narrower 
than the first two, flagellum composed of thirteen joints. 
Second antennae more than half as long as the body, first three joints of the 
peduncle short, fifth joint one and a half times as long as the fourth and somewhat 
narrower, flagellum composed of nearly one hundred joints. 
