Aniphipoda with notes on a species of Isopoda. 
447 
and armed with a few simple spines. In the male (pi. XX, fig. 3) these appendages 
have the propodus larger and more robust than in the female, more quadrangular in 
shape, palmar margin more transverse and armed with a number of stout peculiarly 
striated blunt spines (pi. XX, fig. 5). 
Third thoracic limbs (second gnathopods) in the female (pi. XX, fig. 7) longer than 
the first, propodus as long as the carpus, rectangular in shape, twice as long as broad, 
armed with numerous tufts of setae, palmar margin almost transverse. In the male 
(pi. XX, fig. 4) these appendages have the propodus rather stouter than in the 
female, the palmar margin armed with stout blunt spines similar to those on the first 
gnathopod of the female. 
The form of the remaining thoracic limbs may be seen from pi. XX, figs. 8-9, 
representing the fourth and eighth thoracic limbs. The last three pairs of thoracic 
limbs are characterized by the rather narrow pyriform shape of the second joint, 
which, in the eighth pair, is nearly twice as long as broad. 
The branchial lamellae of the third to the eighth thoracic limbs have accessory , 
branchiae in ihe form of long cylindrical finger-like processes arising at the base of 
the main lamella on the outside of the peduncle. These accessory branchial 
processes are shorter on the last thoracic somite than on the others and may he 
two in number on some of the gills (pi. XX, fig. .10). 
Third uropods of similar form in both sexes, but in the male (pi. XX, fig. 17) 
considerably larger than in the female and extending well behind the first and second 
pairs. In the female the third uropods only extend slightly beyond the first and 
second pairs. In the male the peduncle is short, about I of the length of the 
outer branch. Inner branch slightly shorter than the peduncle and -| of the length 
of the outer branch. I^atter two-jointed with the second joint | of the length of 
the first, with groups of spines along both margins but only a few setae. 
Telson (pi. XX, fig. 18) cleft almost to the base, lobes dehiscent with their apices 
rounded and armed with one spine and one or two setae. Lateral margins with one 
or two (in one case three) spines. 
Length of males and females, 15 mm. 
The description given above applies to those specimens captured in the deeper 
part of L. Biwa, from 20-77 metres, i.e. Stations 5, 6, 8, 12, 14 and 15 in the above 
list, and I have selected these as the types of the species. I have referred all the 
Gammarids captured in ly. Biwa to the same species but a few notes on variation 
may be useful. 
The specimens from Sapporo diftered from those in L. Biwa in having more 
numerous spinules on the pleon somites and in having more setae on the telson and 
a development of setae on the inner margin of the outer ramus of the third uropods. 
An adult male from Sapporo, quite as large as any from L. Biwa, had one pair of 
spinules on the second pleon segment, two pairs on the third segment, three pairs on 
the fourth and fifth segments and five spinules on the sixth segment. Each lobe of 
the telson had two prominent spines and five or six setae while the inner margin of 
the outer ramus of the third uropods bore about fifteen long plumose setae. The 
