Juvenile Tunas—SCHAEFER and Marr 
263 
Fig. 1. Photograph of juvenile Euthynnus lineatus Kishinouye. 
the smaller sizes, but the snout and anterior part 
of the head is rather more extensively pig¬ 
mented in the smaller Euthynnus of these col¬ 
lections than in either Katsuwonus or Neo- 
thunnus of similar sizes. On the smaller of our 
specimens of Euthynnus the lateral pigmentation 
does not extend far below the mid-line, but 
there is a conspicuous series of black spots 
along the bases of the anal fin and following 
finlets. As the fish increase in size the pigmen¬ 
tation extends further down the sides, par¬ 
ticularly posteriorly, until at about 45 mm. the 
pigmentation at the level of the anal fin ex¬ 
tends the entire depth of the fish, although 
shading off ventrally. By the time the fish has 
reached 55 mm. the entire head is rather dark, 
the body is almost black dorsally, shading off 
gradually to a white belly. In some specimens 
of about 45 mm. to 60 mm. the pigment on the 
upper sides is concentrated to form 8 or 9 
extremely faint vertical bars. In the 86 mm. 
specimen these are not visible. The peritoneum 
bears numerous large dark spots dorsally which 
are visible through the body wall in small 
specimens. The caudal fin begins to exhibit 
some pigmentation in fishes of about 50 mm. 
total length. 
In addition to the examination of specimens 
preserved in alcohol, two specimens of 54 mm. 
and 56 mm. were prepared for study of bony 
parts by staining with alizarin and clearing, 
after the method of Hollister (1934). The 
pectoral fin in the two stained specimens has 
29 rays and 27 rays, respectively. These rays 
