270 
PACIFIC SCIENCE, Vol. II, October, 1948 
is still long, but less wide. In a specimen of 
72 mm. total length, the haemal arch is still 
long, but even less wide. In fact, the pedicle 
is divided and contains a large part of the 
haemal arch. In the two smaller specimens, 
the haemal arch is certainly closed on the 18th 
abdominal vertebra and is probably closed on 
the 17th vertebra; it is definitely open on the 
16th vertebra. In the 72 mm. specimen, the 
haemal arch is open on the 17th vertebra and 
closed on the 18th. Kishinouye (1923: 339) 
states that the first closed haemal arch of 
Auxis occurs on the 1st caudal vertebrae 
(= 21st). In an adult specimen examined 
through the courtesy of Dr. G. S. Myers, the 
first closed haemal arch is on the first caudal 
vertebra. This specimen is from Wakanoura, 
Japan, and is referred to Auxis hira. We have 
been unable to examine any adult Auxis from 
the eastern Pacific in order to attempt to re¬ 
solve this apparent discrepancy. C. R. Clothier 
has informed us that one specimen from the 
vicinity of Sebastian Viscaino Bay and two 
from the vicinity of Espiritu Santu Island, all 
identified as A. thazard, have a total of 39 verte¬ 
brae with the first haemal arch on the 21st 
vertebra. It seems unlikely that haemal arches 
that are closed would, with growth, become 
open. Our specimens may, therefore, be juve¬ 
niles of an undescribed species. It is not 
unlikely that the sides of the pedicle fuse with 
an increase in size of the fish so that the haemal 
arch becomes greatly reduced in size. The possi¬ 
bility exists, however, that it may remain 
divided in this form. 
The liver is divided into three lobes. The 
right lobe is almost as long as the visceral 
cavity and bears a prominent hepatic vein on 
its outer surface; the other two lobes are small. 
The stomach is long and lies above the rest of 
the viscera. The caecal mass is considerably 
shorter than the stomach. The intestine is rela¬ 
tively short, straight, and not folded. It runs 
posteriorly along the right inferior side of the 
stomach. There is no air bladder. 
The vertebral count, the great length of the 
right lobe of the liver, the presence of a caudal 
keel, and the absence of an air bladder indicate 
that these juvenile scombroids belong to the 
family Katsuwonidae. The large interspace 
between the dorsal fins and the low ray count 
of the first dorsal, as well as the absence of the 
elaborate "trellis” of the vertebrae, indicate 
that they are Auxis, rather than Euthynnus or 
Katsuwonus. In the larger specimens, gill raker 
and fin ray counts will also serve to separate 
Auxis from the other genera. Positive specific 
allocation must await examination of adult 
specimens from the area. 
A specimen of A. thazard, 17.5 mm. long, 
from the Mediterranean, was described and fig¬ 
ured by deBuen (1932: 36-38). This is some¬ 
what smaller than our smallest specimen and the 
differences between them, such as differences 
in numbers of preopercular spines, etc., are 
probably due to the differences in size. Sparta 
(1933: 16) mentions that specimens of Auxis 
bisus Bonaparte (= A. thazard Lacepede) about 
1 cm. in length have been collected under a 
light at night in the Straits of Messina. Ehren- 
baum (1924: 33-38) reported on 132 juvenile 
A. thazard from the Mediterranean collections 
of the Danish Oceanographical Expeditions. 
His largest specimen was 12 mm. in length, or 
about 9 mm. shorter than our smallest specimen. 
Again, differences between his descriptions and 
our specimens may probably be attributed to 
differences in size. These specimens were ap¬ 
parently taken in May, July, August, and Sep¬ 
tember. He states that Sanzo found ripe ovar¬ 
ies in June and July. Sella (1924) describes 
Mediterranean specimens of A. bisus Bonaparte 
(= A. thazard Lacepede) ranging from 3 to 10 
mm. These are much smaller than our speci¬ 
mens. He states that juveniles up to 10 to 15 
mm. in length are found from the second half 
of June to September 20. He also mentions 
that before a length of 12 to 15 mm. is at¬ 
tained, about six rays are formed in the mem¬ 
brane connecting the first and second dorsal 
