lb. 



Pelvic fin present. A pair of caudal keels on each side. Snout somewhat shorter and 

 nearly rounded in cross-sectional view. Body covered with small elongated bony scales. 

 Many small teeth. Base of first dorsal fin long and close to base of second dorsal fin 

 (Istiophoridae), Figure 1 , B-K 



2a. First dorsal fin considerably higher than body depth at level of mid-body. Pelvic 



fin rays very long with well developed membrane (Istiophonis). Figure IB, IC 3 



2b. First dorsal fin only slightly higher to slightly lower than body depth at 

 level of mid-body. Not sail-like in shape. Pelvic fin rays not as long, with moderately 

 developed membrane. Figure 1 , D-K '* 



3a. Pectoral fin and caudal fin short in specimens of about 90 cm body length. Dis- 

 tributed in the Indo-Pacific Ocean 



Indo-Pacific sailfish, Istiophonis platypterus (Shaw and Nodder), Figure IB 



3b. Pectoral fin and caudal fin long in specimens of about 90 cm body length. 



Distributed in the Atlantic Ocean Atlantic sailfish, Istiophonis albicans (Latreille), Figure IC 



4a. Height of anterior part of first dorsal fin slightly higher than or nearly equal to 

 body depth. Body well compressed. External margin of head between preorbital 

 and origin of first dorsal fin slightly elevated or not elevated (/"('/ra/^n/n/.v), Figure 1, D-H 5 



4b. Height of anterior part of first dorsal fin lower than body depth. Body not well 

 compressed. External margin of head between preorbital and origin of first dorsal 

 fin highly elevated (Makaim). Figure 1 , I-K 



5a. Anterior fin rays of first dorsal fin slightly higher than the remainder; latter nearly 

 equal in height to end of the fin. Anus situated far in front of origin of first anal 

 fin. Second anal fin situated somewhat before second dorsal fin. Figure 1, D-F 



5b. Anterior rays of first dorsal fin somewhat higher than remainder of the fin; the 

 height decreasing gradually posteriorly. Anus situated near origin of first anal fin. 

 Second anal fin situated about under second dorsal fin. Figure I, G-H 



6a. Pectoral fin width less than 6.5 times pectoral fin length and 1.6-2.5 times head 



length 7 



6b. Pectoral fin width more than 6.5 times pectoral fin length and 1.0-1.4 times head 



length Longbill spearfish. Tetraptunis pfluegeri Robins and de Sylva, Figure IF 



7a. Snout short; bill length about 1.6 times head length 



Shortbill spearfish. Tetraptums angustirostris Tanaka, Figure ID 



7b. Snout long; bill length about 1.2-1.5 times head length 



Mediterranean spearfish, Tetrapturus belone Rafinesque, Figure IE 



8a. Pectoral fin wide, its tip rounded. Tips of first dorsal fin and first anal fin 



round White marlin, Tetraptunis alhidus Poey, Figure IG 



47 



