A PRELIMINARY NOTE ON THE FISHES OF LAKE BIWA. 125 



search afteu the males, and the males in turn caress the females, and 

 stirring up the dirt of the river, make the coition. Upon hearing any 

 human sound, they rapidly move their fins and svi^im away. It is due 

 perhaps to this fact, that the name Hasu (Ha Jp Swiftness, and Su ^ 

 Son) is applied to this fish. 



" The largest male sometimes measures over one foot in length. 

 The females are of a blue colour on the back, and silvery white towards 

 the abdomen. They do not exceed seven or eight inches in length. In 

 the months of May and June (of the lunar calender), they have eggs in 

 their bellies, and their flesh is nice. After the cool Autumnal breeze has 

 blown over the lake, the colour of the males becomes similar to that of 

 the female ; their back assuming the blue and their abdomen, the white 

 colour. They are then called " White Hasu " (Shirahasu) ; they now 

 become more fatty and their flesh is very nice to eat. The large males 

 with red coloured fins are called Ketabasu, or Keta-hasu." 



We obtained our specimens in the first days of April, and are 

 therefore nearly two months before the breeding season of the fish. 



The colour of the female is dark-blue on the dorsal third, and of a 

 light silvery blue on the ventral side. The male has in addition to this 

 a flash of rose colour on the ventral half of the body, a line of crimson 

 colour along the lateral line. The border of the upper jaw, the 

 mandibles, the lower angle of the preopercules, and the lower border of 

 the operculum are also of a beautiful crimson colour. The pupil of the 

 eye is indigo-blue surrounded by a ring of crimson colour. The dorsal, 

 the ventral, the anal and the caudal fins are of an orange colour with 

 streaks of crimson between the fin-rays. The pectorals are of a 

 beautiful reddish orange. 



4. Pseudogobio esocinus, Blkr. 



Jap. name Kamasuka, Loc. Matsubara. 



5. Pseudogobio variagatus, Sclileg. 



Jap. name Higai, Aburahae. Loc. Otsu, Matsubara, Maebara. 



This fish differs much in coloration. Small individuals of about 



