Table 2. — Number and (in parentheses) percentage of sailfish with different combinations of fin rays in the anterior 

 and posterior portions of the dorsal fin, in a series of 142 specimens from the uestern Atlantic 



Table 3. — Number and (in parentheses) percentage of 

 sailfish with different combinations of fin rays in the 

 anterior and posterior portions of the anal fin, in a 

 series of 143 specimens from the western Atlantic 



Posterior 



portion fin 



rays 



Anterior portion fin rays 



16 



17 



Number Number Number Number Number Number 



1 11 27 23 4 



(0.7) (7.7) (18.9) (16.1) (2.8) 



1 4 20 33 19 



(0.7) (2.8) (14.0) (23.1) (13.-3) 



portion of both tins, 24.8 percent have six rays in 

 each, 20.f) percent hnve seven dorsal and six anal 

 rays, and the rest (7.8 percent) have six dorsal 

 and seven anal rays. Twenty (about 75 percent) 

 of 27 eastern Atlantic specimens have six rays in 

 both tins. 



The numbei- of pectoral tin rays ranges from 17 

 to 20; 10 (6.9 percent) of 145 western Atlantic 

 specimens have 17, 126 (86.9 percent) have 18, 8 

 (5.5 percent) have 19, and 1 (0.7 percent) has 20. 

 Fifteen of 28 eastern Atlantic specimens have 17 

 rays, 12 have 18, and 1 lias 19. 



All specimens iiave nine npi^er and eight lower 

 principal caudal rays. Counts were 11 or 12 upper 

 and lower secondary caudal rays for several speci- 

 mens (40-216 mm. SL) which were cleared and 

 stained or X-raved. 



T.VBLE 4. — Number and (in parentheses) percentage of 

 sailfish with different combinations of fin rays in 

 the posterior portions of the dorsal and anal fins, in a 

 series of I4I specimens from the uestern Atlantic 



Fin-ray counts given by Robins and de Sylva 

 (1963) for adult Istiopliorus pl<it,ypterus are: 

 dorsal spines, 40 to 49; second dorsal rays, 6 to 8 

 (1 of 59 fish had 8 rays) ; anal spines, 12 to 17; 

 second anal rays, 6 to 8 (1 of 59 fish had 8 rays), 

 pectoral rays, 18 to 21. The difference between 

 their range of 40 to 49 dorsal spines and my range 

 of 43 to 50 rays in the anterior portion of the 

 dorsal fin and their range of 12 to 17 anal spines 

 and my range of 14 to 19 rays in the anterior por- 

 tion of the anal tin may reflect degeneration of 

 several rays immediately ahead of the second 

 dorsal and anal fins and tlieir overgrowth by skin 

 in the adult. A comparison of the percentages of 

 my fish with six and seven rays in the posterior por- 

 tions of the dorsal and anal fins with the informa- 

 tion given by Robins and de Sylva is interesting. 

 Roughly, one-third of their and my (western At- 

 lantic) fish (32.2 percent and 32.4 percent, respec- 

 tively) had six second dorsal fin rays and two- 

 thirds (66.1 percent and 67.6 percent, respectively) 

 had seven second dorsal fin rays (they recorded one 

 fish with eight second dorsal rays, I had none). 

 They recorded these same percentages of sailfish 

 for numbers of second anal rays; 32.2 percent with 

 six, 66.1 percent witli seven, and one with eight 

 rays. My counts are different; they show 46.2 per- 

 cent with six rays, 53.8 percent with seven, and 

 none with 8 in the posterior portion of the anal fin. 



REGRESSIONS OF BODY PARTS 

 ON TRUNK LENGTH 



Comparisons of the changes in various body 

 parts of fishes during development have been 

 variously based on standard, fork, or total length. 

 The snout and caudal rays are .so frequcntlj- 

 damaged in the billfishes that measurements in- 

 volving one or both of these parts may be inaccu- 

 rate. Body length, recommended by Rivas (1956) 

 as the preferred ba.se length for billfishes, is the 

 distance between the tip of the mandible and the 



YOUNG OF ATLANTIC SAILFISH 



183 



