Auxis thazard 



Auxis rochei 



Specimen No. 7 Standard length 88.5 mm. 



Specimen No. 28 Standard length 94.0 mm. 



(free parapophysis) 

 Specimen No. 37 Standard length 123.6 mm. 



Specimen No. 23 Standard length 124.6 mm. 



Figure 24. — Caudal vertebrae o( Auxis thazard (left) and A. rochei (Watanabe I964I. 



fin to the distance between the origin of the first and sec- 

 ond dorsal fins. Watanabe found that in A. thazard, the 

 first free parapophysis occurred most frequently on the 



r~l Auxis rocl<ei 



F1 Auxis tliazord 



nil 



nn n n n 



H 



-, nn n n n 



m 



■ nn n n nO n 



„ nn n n 



mH 



riEi n D n nn 



90 100 no 120 130 140 



STANDARD LEIWTH(mm) 



23d vertebra, whereas in A. rochei, it was on the 21st or 

 22d vertebra on SO'^ of the specimens; however, there 

 were some in which it occurred on the 23d vertebra. 

 Furthermore, the inferior foramen in young specimens 

 occurs on the 27th or 28th vertebra in A. thazard and 

 usually on the 29th and 30th vertebra in A. rochei. 

 Watanabe also observed that the ratio of the length of 

 the caudal to the precaudal vertebra for young speci- 

 mens was 0.973 or less in A. rochei and 0.985 or more for 

 A. thazard. This character also changes as growth oc- 

 curs; therefore, the stage of growth needs to be consid- 

 ered in making a diagnosis. Figure 26 shows a plot of 

 the ratios — body height at the origin of the anal fin to 

 the distance between the origins of the first and second 

 dorsal fins — on standard lengths and except for a single 

 specimen which showed an intermediate value, those for 

 A. thazard tend to be higher than for A. rochei. 



80 90 100 110 120 130 140 220 230 240 250 260 



STAtiJDARD LENGTH (mm) 



Figure 25. — Comparison of the length of the free parapophyses of 

 the caudal vertebrae between Auxis thazard and A. rochei (Wata- 

 nabe 1964). 



Figure 26. — Comparison of the value (a/b) between individuals of 

 Auxis thazard and A. rochei (Watanabe 1964). (a = Body height 

 at anal origin; b = length of first dorsal to second dorsal origin.) 



30 



