of the head have the form of a long ellipse. The lateral line is well developed and is curved 

 upward conspicuously over the pectoral fins, posterior to which it runs in an approxinnately 

 straight line along the center of the sides of the body. 



(f) Fins 



All of the fins except the ventrals are well developed in nnost families. The ventrals are 

 not developed at all in the broadbill, and in the istiophorids they are represented by I to 3 thin 

 rays. However, none of the fishes occurring around this island have ventrals composed of only 

 one ray. 



The first dorsal fin commences anterior to the posterior end of the cranium and the num- 

 ber of rays is 40 or more. The most anterior ones are spines, those in the longest portion of 

 the fin are soft rays, their number being about 10, and posterior to these we again find spines. 

 In the first dorsal of the broadbill the anterior spines and soft rays are remarkably developed, 

 their height exceeding the body depth, but their length decreases rapidly posteriorly, and beyond 

 about the 20th ray they are not developed outside of the body. In the Istiophoridae all of the rays 

 of the first dorsal fin are developed outside of the body, but the greater part of the fin can be 

 folded away into a sort of sheath which is developed along the dorsal surface. 



Jordan and Evermann classified the istiophorids into genera based on the characteristics 

 of the first dorsal fin as follows: 



The dorsal fin of the shortnosed spearfish is not very high and its anterior lobe is small 

 (genus Tetrapturus ). In the black marlin, striped marlin, and white marlin of the genus Makaira 

 the dorsal fin is low with a high anterior lobe and the anterior spines are thickened. In the 

 sailfish (genus Istiophorus) the dorsal fin is very high and the ventral fins are very long with 

 their rays fused together. Thus the dorsal fins of the Istiophoridae present various conspicuous 

 characteristics. 



The pectoral fins are very much developed, their length being only slightly less than the 

 body depth (measured around the side of the body). The pectorals are smallest in the shortnosed 

 spearfish. A groove in the side of the body into which the pectoral fins fit, such as is seen in 

 the tunas, is not developed in the spearfishes. The structure of the pectoral fins of the white 

 marlin is of a special type which differs from the other spearfishes. In the other fishes of both 

 the family Istiophoridae and the Xiphiidae the pectoral fins can be pressed tightly against the 

 sides of the body, but it is not possible to do so with the white marlin without breaking the joints 

 between the pectoral girdle and the pectoral fins. For this reason it is very simple for us to 

 find the white marlin among the spearfishes lined up in the fish market, one glance sufficing to 

 show their location. Where a pectoral fin sticks out into the air at right angles from the body 

 among a group of spearfishes, we know that it is a white marlin (see fig. 2). 



The ventral fins are most developed in the sailfish and developnnent is poorest in the 

 white marlin, followed by the black marlin. The first anal fin is well developed in both families. 

 In the Istiophoridae there is all along the base a sheath into which the greater part of the fin can 

 be retracted. In the genus Makaira the first anal fin is alnnost identical in form to the anterior 

 portion of the first dorsal, the first few rays being similarly thickened to a great degree. 



The second dorsal and the second anal are well developed in the family Istiophoridae, each 

 of them having 6 or 7 rays, but in the broadbill they are poorly developed and each have only 

 4 rays. 



The caudal fin is very well developed in both fannilies. In the broadbill the upper and lower 

 lobes are both quite broad ajid the angle between them is rather small. In fishes of the family 

 Istiophoridae both lobes are narrower than in the broadbill and the angle between them is large 

 so that they are broadly forked. 



10 



