COMPARATIVE STUDY OF SCOMBKOID FISHES. 403 



fishes— narrow pi-eiuaxUlary which is not prota'actUe and wants a doi'sal process, 

 nnd a small supplementary bone attached to the posterior end of the premaxiEiry. 

 This family has remote relations to the Cybiidae. The genus Grammalorcymts 

 of the Cybiidae has tlie same numljer of vertebrae as the mackerels, and pyloric 

 coeca are also more or less alike. 



St.\rks (69) rightly remarks that " if we could eHminate the genus Scom- 

 ber, the family (Scombri dae in wide sense) wfiuld be much more compact, as 

 it sbmds fai-tlier fi'om the otiier genera tlian thoy do from each other." 



Mackerels are rather small, grow to a length of about 40 cm. and a weight 

 of about one kg. They swim generally in the middle or lower layers of the 

 coastiil water, and enter into lays and inlete, in shoals. Widely distributed in 

 terapei-ate and subti-oiMcal regions. 



Key to the generft o£ the Scombriclae. 



Body elongated and fusiform, vomer and palatines toothed Scomber. 



Body deep and compressed, vomer and palatines toothless, gill-rakers very 

 long, visible from the gape of the mouth, interspinoua bones of the second 

 dorsal and the anal are flattened Rastrdliger. 



Genus Scomber. 



Scomber, Linnaeus (s. str.) 1758; Ciivier, I8l7. 



Teeth minute, in botli jaws in one row, on the vomer in paired obhque 

 patches and on palatines in one row. 



Only two good species are known, and only one species is found in the 

 Pacific Ocean. 



Scomber japonicus Houttouyn. 



Saba. 



Figs. 1, 7, 16, 28-30. 



Scomber japomcxLs Honttoiiyn, Memoires de Harlem, XX , 331, 1782 ; Lacei)ede, Hist- 

 Xat. Poiss. m, 45, 1802 ; Cuv. &, Val. Hist. Nat. Poiss. VIH, 54, 1831 ; Kishinouye, 

 Sni. Gak. Ho, I, 4, PI. I, Fig. 1. 1915. 



Scomher pneumatopfuirus Schlegel, Fanna .Iaix)n., Poiss. 94, Tab. 47, Figs. 1, 2, 185U. 



SconJjer saha Bleeker, Yerli. Bat. Gen. XX\"I, 95, 1S57. 



Sco'iiber janesahn Bleeker, Verb. Bat. Gen. XXVI, 96. 1857. 



.» Scornber iapeinocephalus Bleeker, Verb. Bat. Gen. XXVI, 97, Tab. 7, Fig. 2, 1857. 



Scoinier colias Kishinouye, Joum. Fish. Bureau, II, 1, Pis. I, II, 1893. 



D. 9-12, 12, 5. A. 1, 12-13, 5. Yert. 14 + 17. GiU-rakers 13+23. 

 Body fusiform and compressed, its height nearly equal to the length of the 

 head. Teeth minute, about 60 in each jaw. The scales in the dorsal half of 



