Nine species have been reported for this genus, of which five 

 occur in the Indo-Pacific regiono The following single species occurs 

 in Japanese waterso 



Zo Istiophorus orientalis (Temminck & Schlegel) 



In Japanese bash"ok:a.1ikis i nor age p hauO p baren , oba , sugiyama, , 



The first dorsal fin has 44 to 47 rayso The first 3 are spines^ 

 the following 9 have branched tips, and the remaining posterior rays 

 are again unbranched spines o The second dorsal fin has 67 soft rayso 

 The first anal fin has 2 spines and 11 soft rays^ and the second anal 

 fin has 6 soft rays„ The vertebral count is 12 / 12 s 24„ 



The body length is 3o2 times the head lengthy 6,3 times the 

 greatest body depth, and 7„8 times the body depth at the insertion of 

 the first anal fin. The head length is lo4 times the snout length, 

 and 7o5 times the interorbital space,, The length of the snout is 3 

 times the length of the head excluding the snout„ The head length 

 without the snout is 3,, 7 times the diameter of the eye,, The distance 

 from the eye to the insertion of the first dorsal fin is 3»8 times the 

 diameter of the eyOo The greatest body depth is 4c. 6 times the depth 

 of the caudal peduncle^ The length ratio of the upper and lower jaws 



The body is long and slender, greatly compressed laterally, with 

 the caudal portion gradually becoming cylindricalo There are keels on 

 each side of the caudal peduncleo The upper jaw is more than twice the 

 length of the lower jaw, and there are rasp-like teeth on both jawso 

 The scales are bony and slender, and almost completely buried in the 

 skino The lateral line is simple and clearly visible. 



The first dorsal fin is remarkably developed, its height being 

 far greater than the body d eptho The height of the third spine of this 

 fin is lo3 times the body deptho The following 8 or 9 fin rays gradually 

 decrease in height, but thereafter the fin rays again increase in height 

 until the 14th or 15th ray, where a maximum height of over twice the 

 body depth is attained. Posterior to this point the height of the fin 

 decreases rather rapidly. Consequently, the outline of the first dorsal 

 fin is indented anteriorly and arched posteriorlyo The pectoral fins 

 are rather short, being 0.8 to 0„9 times the greatest body depth. The 

 ventral fins are well developed, their tips reaching to the vent. Their 

 rays are incompletely fused together, and consist of 1 spine and 2 soft 

 rayso The first anal fin is well developed, but is not falciform in 

 outline. The second dorsal and the second anal fins are roughtly 

 symmetrical, being almost the same shape and size. The caudal fin is 

 large and strong. Its upper and lower lobes are narrow, but the angle 

 between them is great. 



Palatine teeth are poorly developed. The cranium is rather long. 

 The vertebrae are long and the anterior edges of the neural and haemal 

 spines are somewhat arched in outline. In general, the neural spines 

 of the ventral vertebrae are small, and consequently the space between 

 spines is great. 



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