COMPARATIVE S^R'DY OF SCOMBROID FISHES. 457 



They jivo fouuil not ouly in bjth jaws, but also on tiio pUntiiies nnd sm^- 

 tinies on the vunior too. Teeth on the palatines «re in single row. Tlie right 

 lolx' of the liver much elongated as in the gcnns Auxis. It is remarkable 

 that the chief cutjineons artery rans along the dorsal external side of the chief 

 cutaneous vein, quite cjntrary to the case in all the other forms of the j)leco3tean 

 fishes, and the dorsal segmental liranches of the chief cutaneous vein pass 

 over the accompanying artery, Mliich is a little more or less deeply iml^eddod 

 in the muscle. The degenerated hypaxial cutjineous artery lies ventral, that is 

 external and similarly to the accomptnying vein. Hypaxial, cutaneous blood- 

 vessels are bent in a zigzag line. They have no connection with the vascular 

 plexus, nourishing the dark red pji-tion of the lateral muscle. Tlie subspinal rod 

 of the vascular plexus is also well developed, bnt the rod is separated from the 

 vertebral coliuun hy the development of the epihaemal process, between the 

 vertebral column and the haemal canal. Tlius the inferior foramen is remarkally 

 larger than in the genus Katsuivomis. 



Dark markings in the naked part of tlie back, and generally sume greyish 

 spots in the pectoral region abo^e the -soutrals. 



Fishes of this genus attain about the same size as the striped bonito. 

 They are degenerated forms, derived from the genus Katmwomis. Voracious 

 fishes of temperate and tropical seas, not forming large schools, and often ap- 

 proaching the coast, until recently onlj- one species was known, but I have 

 fjund other two species in the Pacific, quite difiercnt from the Atlantic 

 si^ecies. 



Key to the species of the genns Etiihynmis. 

 Vomerine teeth present. 



Dark oblique bands on the back E yaUo. 



Dark longitudinal bands on the back E. lineatus. 



Vomerine teeth absent E. atteterata. 



Euthyiinus yaito Kishinouye. 

 Yaito, hiragatsuwo, olx)sogat3uwo, segatsuwo, suma, uramawarigatsuwo, wata- 

 nabe, yaitopara, yaitosuma. 



Figs, 2C, 54, 58. 



Thyrmtis thunniTia, Sohlegel, Faiuin .Tnpon. Poiss. 95, Tab. 48. 1850. 

 .' nynnus affirds. Cantor, Cat. JIalay. Fish. 106, 1850. 



