COMPARATIVE STUDY OF SCOMBROID FISHES. 
3S5 
inclined to believe that the young fish, about 27 cm long are two years old, 
and young ones about 35 cm are three years old, and sexually mature. Thus 
the growth of our common mackerel seems to be nearly the same as that of 
Scomber scombrus of the Atlantic. However, this rate of growth is slow compared 
with that of other scombroid fishes, and needs confirmation. 
So far as I know, eggs of the scombroid fishes are pelagic, spherical, and 
each egg is provided with a pretty large oil-globule. There are very little 
distinctive characters in eggs of different species. Eggs of Cybium niphonium 
are very large, the largest among the pelagic eggs, found in the Inland Sea 
in spring. 
In 1920 I found a larva of Cybium niphonium, 8 mm in length, among a 
bunch of immature forms of various fishes from the bunt of a seine, hauled to 
catch the adult of that species, on June 7th, in Kagawa-ken. The larva has 
a very long snout, powerful jaws with large teeth, preopercle with three spines, 
very short but broad precaudal portion, pigment spots on the head and along 
the ventral median line of the caudal portion. An immature fish of 33 mm in 
length has a larger head and broader body than the adult. The preopercle is 
armed with about four spines. The pectoral is 
small and rounded, and the posterior portion of 
the second dorsal and anal begin to be sepa¬ 
rated to finlets. In this specimen the precaudal 
portion was elongated to a nearly similar length 
as the caudal. The first dorsal is higher than the second. An immature fish 
of 100 mm, caught late in July, 1914, has a still broader body than the preced¬ 
ing. The first dorsal is lower than the second dorsal, and the caudal is much 
- 
Fig. S. Cybium niphonium 
(immaturej. 4/3. 
Fig. T. Cybium niphonium (immature). Nat. size. 
developed. The general appearance is quite similar to that of the adult. The 
colour markings are however wanting. In the immature fish below this size 
