COMPARATIVE STUDY OF SCOMBROID FISHES. 
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lower jaw. Tliey are formed in alveoles and are replaced by new ones coining 
out between the old. In the Scombridæ the teeth are very minute. Indeed 
the Japanese name “ saba ” for the mackerel means minute teeth in our old 
language. The vomerine teeth when present are arranged in two lateral 
patches, and the palatine teeth when present are in one row only. In the 
Cybiidæ the teeth are well developed, long, curved, laterally compressed, and 
generally trenchant at the edges. Thus seerfishes are voracious, and often hurt 
fishermen and damage fishing apparatus too. Teeth on the vomer and 
palatines are villiform. In the Plecostei the teeth in jaws are small, conical 
and curved. In the Thunnidæ villiform teeth are found on the vomer, 
palatines, and pterygoids. Mesopterygoid teeth are remarkable, as they are 
not found in the other fishes. In the Katsuwonidæ the teeth are found in 
both jaws only ; but in the genus Euthynnus palatines and sometimes the 
vomer too are toothed. In these cases the teeth are arranged in one row 
only, and they are rather large. 
The eyes are comparatively small in the Cybiidæ, being contained more 
than 7-10 times in the length of the head, and more than 30-40 times in 
the total length of the body ; but they are large in Gyrnnosarda. In the 
Scombridæ and Plecostei the eyes are large, being contained less than 6-10 
times in the head, and 18-27 times iu the body. In the Scombridæ the 
adipose eyelids are remarkably well developed. In the Cybiidæ and Plecostei 
the eyelids scarcely cover the eye-ball. T lminus germo and Parothunnus 
mebachi have large eyes, these tunnies descend to tie deeper strata of waters. 
The eye-capsules are well developed and more or less calcified in the Plecostei. 
Lateral Line. 
The lateral line more or less undulates. In the Scombridæ, however, the 
undulation is insignificant, being nearly straight from the nape to the caudal 
peduncle, running more or less parallel to the dorsal median line o: the body, 
and the perforated scales in the line are only a little modified from other 
scales. In the Cybiidæ the lateral hue runs generally paralled to the dorsal 
median line of the body for some di dance from the nape, and at the caudal 
part the lateral line nearly coincides with the lateral median line of the body. 
These two portions of the lateral line are connected by an oblique portion. 
