352 



KAIIAKICHI KISHINOUYE : 



ventral side of the skull, in the otic r^on. 



H 5 



Fig. K. Dorsal view of the brain. 



1, Scomber japonicus ; 2, Cijhium niphonhim ; 3, Thimmis orkriialls ; 4, Thunmis germo ; 

 5, Katsuwonus pelamis ; 6, Auxis mam (dorsal & lateral) ; 7, Evihynnus yaiio. 



In the Plecostei the brain is thicker than that of the Teleostei, and the 

 cerebellum covers the whole length of the brain, behind the prosencephalon. 

 The external surface of the prosencephalon aud cerebellum is not flat. The 

 former is divided into fom- longitudinal lolxis, and the latter into several areas 

 by the median longitudinal and transverse grooves. 



GangHa of the sympathetic nei-ve are foimd in the haemal canal, one in 

 each body-S(^ment, and when the canal is filled with the vascular plexus, they 

 are embedded in it. 



The otohth is ititlier thick and the parts on each side of the median groove 

 are ueai'ly equal in the Scombridae. In the Cybiidae one side is longer than 

 the other, and in Gymnosarda the longer side is very much elongated and is 

 nearly twice the length of the other. In the Thimnidae the otohth is straight, 

 and one side is much longer than the other. In the Katsuwonidae the otohth 

 is very slender and the parts on both sides of the groove are eqtially well 

 developed, the hind end being more or less swollen. 



