114 



T. KITAHAKA 



The male fish is, as a rule, a little smaller than the female ; the 

 former being about 45 mm., and the latter, about 50 mm., long. 

 The left ovary, when fully developed, reaches 11 mm. in length and the 

 right 9 mm., each with a semicircular notch on the median side 

 for reception of the globular air-bladder. Nearly 400 ova are found in 

 the two ovaries. The ovum, when ripe, is round, colorless and 

 transparent and about 0.75 mm. in diameter. The vitellus contains no 

 oil globule. The egg-envelope consists of two layers, the outer of 

 which is sticky and is of a reticular structure showing for the most 

 part slit-like meshes (Pl. V., fig. 2 & 3). The ovum, when deposited, 

 sticks itself by that outer layer to any foreign solid body ; the layer 

 eventually splits and separates off from the inner layer except at the 

 micropyle, and by turning itself inside out, forms a sort of stalk by 

 which the egg is fixed. The process is just like that seen in the egg of 

 Osmerus, Hypomesus, Plecoglossus, Salanx, Gobius, &c. The egg of 

 Leucospaiion petersi then gradually swells up, elongating at the same 

 time, so as to assume a club-like shape. 



The fish never go up stream to a great distance, but remain within 

 5 or 6 km. of the rivermouth, burrowing under stones somewhat larger 

 than the wrist and which are for more than half their height buried in 

 the s and of the river bottom. In that situation, the females find a safe 

 cradle for depositing eggs. These are attached in patches (but not in 

 piles) to the under surface of the stone. One such patch usually 

 consists of about 350 eggs all nearly in the same stage of development, 

 and seems to be a spawn from a single female. The club-shaped egg 

 measures 30-35 mm. in length and 1.0-0.8 mm. in diameter, tapering 

 towards the basal stalk (Pl.V., fig. 4). The vitellus too is of a somewhat 

 elongate form ; the blastoderm is always found on the side directed 

 towards the stalk, while the head of the embryo develops on the 

 opposite side. The embryo can be made to slide freely from one end to 

 the other but not to turn over within the envelope. Concerning the 

 period of hatching and further history of the young fish I have no 

 observation at present. Nevertheless it may be presumed that after 



