YOUNG JACK CREVALLES 



433 



has an inflection followed by a decrease in head 

 growth rate; and the other species evidenced a 

 single regression line within the size ranges that 

 were considered for each. The species can be 

 adequately compared between about 25 mm. and 

 88 mm. standard length . C. latus apparently has 

 the fastest head growth rate and crysos the 

 slowest (0.32-and 0.26-mm. increase in head 

 length per 1.0-mm. increase in standard length). 

 C. bartholomaei and latus apparently average the 

 greatest head lengths and crysos and ruber the 

 least at comparable body lengths. 



Eye diameter. — A composite graph of the re- 

 gression lines for eye diameter on standard length 

 for the five common species is shown in figure 11. 

 Inflections occur in this relationship for crysos, 

 ruber, and hippos at approximately 22 mm., 34 

 mm., and 55 mm. standard length; and bartholo- 

 maei and latus evidenced no inflections in the size 

 range of each that was treated statistically. The 

 species are adequately comparable between ap- 

 proximately 16 mm. and 83 mm. standard length. 

 Above 22 mm., bartholomaei apparently has the 

 fastest eye growth rate and above 34 mm., ruber 

 apparently has the slowest (0.095-mm. and 0.058- 



mm. increase in eye diameter per 1.0-mm. in- 

 crease in standard length). C. bartholomaei and 

 latus apparently average the greatest eye diameter 

 and crysos and ruber the least at comparable body 

 lengths. 



A decrease in the eye growth rate of bartholomaei, 

 as suggested later, causes latus to average the 

 greatest eye diameter above approximately 100 

 mm. ; and the large eye size of latus has earned for 

 it the common name of "horse-eye jack." 



Snout length. — A composite graph of the re- 

 gression lines for snout length on standard length 

 of the five common species is shown in figure 12. 

 The species can be adequately compared between 

 16 mm. and 89 mm. standard length. C. bartho- 

 lomaei apparently has the fastest snout growth 

 rate and crysos and hippos the slowest (0.11-mm. 

 and 0.08-mm. increase in snout length per 1.0- 

 mm. increase in standard length). Above ap- 

 proximately 20 mm. standard length, bartholomaei 

 apparently averages the greatest snout length 

 and hippos the least at comparable body lengths. 

 C. dentex may average a snout length similar to 

 that of bartholomaei. 



Gill rakers. — The relation of the numbers of 



25 



50 75 



STANDARD LENGTH IN MM. 



100 



125 



Figure 11. — Comparison of the regression lines for the relation of eye diameter to standard length for five species of 



Caranx. 



