New Records for Juvenile Albacore — Yoshida 
approximately 75-90°. The first ventrally pro- 
jecting parapophysis is on the 7th-9th vertebrae. 
The posterior margin of the basioccipital, 
when viewed laterally, makes an angle of ap- 
proximately 90° or more with the axis of the 
vertebral column in specimens smaller than 19 
cm, and an acute angle in specimens about 25 
cm and larger in standard length. 
The intestine has the two folds characteristic 
of Thunnidae (Godsil and Byers, 1944). 
Only one specimen had its first dorsal fin 
membranes intact; the fin membranes are cov- 
ered with black pigmentation. 
DISCUSSION 
Although no attempt was made to study all 
the differences in the morphology of adult and 
juvenile albacore, a few of the more obvious 
ones were noted in some detail. As indicated 
earlier, the flattened haemal spine on the first 
caudal vertebra becomes definitive early in the 
445 
life of albacore, since a juvenile 6l mm in stand- 
ard length already possessed this character. A 
meristic character that also develops early is the 
gill raker count, for all of the juveniles already 
possessed the full adult complement. However, 
several morphological features of adult albacore 
were still in their early formative stages in the 
juveniles. These were the orientation of the 
parapophyses on the vertebrae preceding the 
ninth vertebra, the angle the first haemal arch 
makes with the axis of the vertebral column, 
the orientation of the bones constituting the 
first haemal arch, and the shape of the posterior 
margin of the basioccipital. 
According to Godsil and Byers (19 44) the 
parapophyses preceding the first haemal arch 
extend laterally in adults. In juveniles the tips 
of the parapophyses on the vertebrae as far 
anterior as the seventh may project ventrally. 
Presumably, with growth the anterior parapo- 
physes tend to straighten out and extend later- 
Fig. 3. Portion of axial skeleton of juvenile albacore showing unique, flattened haemal spine on first 
caudal vertebra. 
