parts, but in juveniles they are both singleo The pectorals are placed 

 low on the body., The ventrals are made up of 3 raysp but they are fused 

 together and appear externally to be a single rayo There are two keels 

 on each side of the caudal peduncle ^ and the lobes of the caudal fin 

 are narrow and widely bifurcateo A lateral line is present^, but while 

 it i s clear in some specimens it is extraordinarily obscure in others. 

 Some individuals have a single lateral line, while in others it is 

 complex in form. There are 24 vertebrae, which can be described by the 

 formula 12 / 12 in some individuals and by 11 / 13 in otherso The ribs 

 are well developed;, but they are headless [^t / and there are no supra- 

 costalso The air bladder is a mass of numerous small spongy chamberSo 

 There are similar air chambers in the muscles of the belly between the 

 anal fins. The family is divided into two subfamilies. 



Key to the Subfamilies 



lo The vertebrae are 12 / 12 g 24o The body is slender with the 

 height of the first dorsal exceeding the depth of the bodyo 

 The anterior portion of the first dorsal has a concave out- 

 lineo The lateral line is single and clearly discernibleo 



The ventral fins are generally well developed o.o .o„oo 



ooooo...oo..»o..»„o«oooi>..oaoo..,...o Subf sjiii ly Tot rBptu ri nao 



2o Vertebral formula 11 / 13 s 24o Body stout^, height of first 

 dorsal less than body depths height of the fin decreases 

 sharply posterior to the 4th or 5th ray„ Lateral line 

 obscurej, may be single or complexo Ventral fins generally 

 short oi,»i,o».ooooooo«oooo€,ooao.«o«oooo«oo Subfamily Marlinae 



Subfamily Tetrapturinae 



Body slender„ trunk markedly compressed laterallyo The first 

 dorsals at its highest portionp exceeds the body depths and its 

 anterior portion is concave in outlineo The lateral line is single 

 and clearly discernibleo The ventral fins are generally longo There 

 may or may not be transverse rows of spots on the sides of the bodyo 

 Vertebral formula 12 / 12 s 24o 



Key to the Genera 



lo Snout short, no transverse bands on the sides of the bodyo 



c». ,...„«u Genus Tetrapturus 



2„ Snout longj transverse bands on sideso... ooo see 3 



3o 



3-lo Dorsal fin remarkably highg its central portion far 



exceeding the body deptho Body remarkably slender 



Genus Istiophorus 



r>aooooooo 



55 



