and somewhat lamellar with sharp projections„ Posteriorly 

 there is a long sword-shaped procesSo This process is 

 usually remarkably large^ 



The pelvic girdle is a pair of bones that support the 

 ventral finso These bones are buried in the abdominal wallo 

 The right and left bones are joined together and are composed 

 of an anterior external portionj, an anterior internal portion, 

 and a gladiate procesSo The juncture between the right and 

 left bones involves the anterior internal portions and the 

 gladiate portions o 



The vertebrae number is 39 in this family of fisheso Of 

 these 18 are abdominal vertebrae and 21 are caudal vertebrae^ 

 so the formula is 18 / 21 s 39, All of the vertebrae are 

 firmly articulated with each other,, and except for the most 

 posterior J, that is the two directly anterior to the caudal 

 fin, they can hardly move to the left or right,. As noted 

 abovoj there is not too great a difference between the numbers 

 of the abdominal and caudal vertebrae ^ but the hemal spines 

 are also well developed on the abdominal vertebrae so it is 

 rather easy to mistake them for caudal vertebraoo It will 

 be noted also that the hemal spines of the anterior abdominal 

 vertebrae are curved forwardo The form and structure of the 

 vertebrae differ markedly depending on their positiono 

 These differences are most marked at the anterior and posterior 

 ends and are inconspicuous in the central part of the spinal 

 columno Four pairs of processes are well developed;, but the 

 anterior neural process is particularly sOo Some of the 

 abdominal vertebrae also have lateral processeso The first 

 vertebra is very short and is firmly joined with a serrate 

 suture to the posterior part of the skull in such a way that 

 many scholars have overlooked ito 



The ribs are developed on vertebrae posterior to the 

 second onej they are broad and compressedo 



iit Viscera 



The air bladder is generally well developed, but it is 

 lacking in the koshinaga ( Neothunnus rarus )o The air bladder 

 of the albacore is slender and extends the whole length of 

 the body cavity with a swollen portion at the anterior tip 

 on the dorsal side on the center line of the bodyo In the 

 tuna (black tuna) the bladder is broad and triangular in 

 shape with its aiterior edge forming a straight lineo The 

 bladder in the big -eyed tuna is slender and extends the whole 

 length of the body cavityo It has two swellings at its 

 anterior tipo In the yellowfin it i s simply a slender sac 

 protected by thick connective tissuoo 



