336 kamakichi kishenouye : 



Vertebral Colujix. 



The general feature of the vertebral column of the different ty^ies of the 

 scombroid fishes may easily be understood by examining Plate XIV, showing 

 the middle ti-ausveise section of veiiebrae. 



In the Scombridae (fig. 30) the numbei' of vertebrae is not large, being 

 31 in total, and the number of the precaudal vei'tebrae is nearly the same as 

 that of the caudal. The vei'tebrae are small, longei' than broad, nearly equal 

 in size and form, and are articulated with each other rather loosely by mestus 

 of short, small zygapjphyses. In Scomber Japoniciis, however, the anterior 

 zygapophyses, both supaior and inferior, are very broad in the caudal vei-tebrae, 

 and then' anterior margin is divided. The articulating surfaces of the first 

 vertebra with the skull are two, sepai'ate, and tmTied axially, just opposite to 

 the ordinary case. Thus a i^air of stout processes at the dorsal comei' of the first 

 vertebra gras^DS the posterior end of the basioccipital (fig. 30, C). The nem-al 

 spine LS nearly equally slender, throughout the whole length of the vertebral 

 column, and the first spine is never free. The anterior concavity of the 

 vertebra is a little shallower tlian the posterior. The nenriil and haemal spines 

 are nearly sti'aight, oblique, and genenxlly thcj are compressed auteroposteriorly. 

 The parapophyses are not develo^xid, and the haemal spine is scarcely developed 

 in the precandal r^on. Almost all the i^recaudal vei'tebrae have theh" neural 

 canal divided into two. The lower canal is for the spinal cord, it is entirely 

 covered by a bony roof, separated fi-i )m the upper canal for the dorsal ligament. 

 The lateral transverse ridge in the anterior precaudal vei'tebrae is quite peculiar 

 to this family (fig. 7). Tlie last vertel>ra is not fused with the hypui-al bones. 



In the Cybiidfie the total number of vei'tebrae is vei'y variable, generally 

 over forty. The least number of them in my collection is thh-ty one in the 

 genus Grammatorcymiß, and the maximmu uumlier sixty four in Acanthoci/bivm 

 solandri. The relative numljer of the precaudal and caudal vei'tebrae also 

 varies. Generally the precaudal vei'tebrae are less in number than the caudal. 

 In Acanthocijbium solandri and Sarda o)'ientalis, however, the pi-ecjiudal vei'tebrae 

 are more numerous, wliile in Sarda ckilensis and Gymnosards nuda the number 

 of vertebrae in both regions is exactly the same. Vei'tebrae ai'c generally very 

 short, disk-like near both exti'euiities of the bixly (fig. 41). In most vei'tebrae 



