YOUNG JACK CREVALLES 



507 



appears at about 120 mm. On 770-mm., 795- 

 mm., and 830-mm. specimens, only the first six 

 spines are connected, and the seventh and eighth 

 spines are completely covered by an overgrowth 

 of skin. Ginsburg (1952: 94) described a similar 

 spine condition for a specimen of about 585 mm. 

 (converted). 



The regression of length of the third dorsal spine 

 on standard length is shown in figure 86 and 

 table 20. A line fitted to this regression for speci- 

 mens from 15.3 to 110 mm. standard length shows 

 a proportional rate of increase for the two variates 



within this size range (0.11-mm. increase in spine 

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

 The position of the coordinates of the "latus 

 and/or hippos" specimens may indicate that a 

 faster spine growth rate prevails for specimens 

 below approximately 15 mm. The position of the 

 coordinates of the four largest specimens of 

 hippos in figure 86 below the extension of the 

 calculated regression line and of the coordinates 

 of specimens up to 795 mm. (fig. 90) suggests 

 that a decrease in spine growth rate occurs be- 

 tween approximately 250 mm. and 300 mm 



Table 20. — Caranx hippos: Statistics describing regressions of body parts on standard length 



i = mean of independent variable x 

 tf=mean of dependent variable y 

 N= number of specimens 

 6 = rate of increase of y 

 a = (/-intercept of regression line 

 Sy' j = standard deviation from regression (standard error of estimate) 



Anal spines. — II and I. The first spine averages 

 longer than the second from 15.3 to 20.4 mm. 

 standard length; above 23 mm. the second spine 

 is the longer. An interspinous membrane con- 

 nects the second and third spines to about 25 mm. 

 (figs. 81 and 82). 



Dorsal soft-rays. — 19 to 21 (table 21). Nichols 

 and Roemhild (1946, fig. 1) indicated 2 specimens 

 out of 42 with only 18 dorsal soft-rays; the other 

 40 were within my range. The posterior rays are 

 branched at 15.3 mm. standard length (fig. 81). 

 The extension of the anterior 5 rays to produce the 

 fin lobe has begun by 25 mm. and is advanced by 

 80.5 mm. (figs. 83 and 84). The second ray 

 averages the greatest length to about 27 mm. ; 

 above 27 mm., the first ray is longest. The third 

 spine averages a greater length than the longest 

 soft-ray to about 34 mm.; above 34 mm., the ray 

 is longer (fig. 86) . 



The regression of length of the first dorsal soft- 

 ray on standard length is shown in figure 86 and 

 table 20. A line fitted to this regression for 

 specimens from 15.3 to 164 mm. standard length 

 indicates that a proportional rate of increase is 

 maintained for the two variates from about 25 to 



164 mm. (0.19-mm. increase in soft-ray length 

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

 alinement of the coordinates of specimens of hippos 

 smaller than 20 mm. and of the "latus and/or 

 hippos" specimens suggests that-a slower soft-ray 

 growth rate prevails below approximately 25 mm. 

 The position of the coordinates of larger specimens 

 (fig. 90) suggests that soft-ray growth may 

 continue at the same proportional rate up to 

 830 mm. 



Table 21. — Caranx hippos: Correlation of the numbers of 

 dorsal and anal soft-rays of 132 specimens 



[The upper number in each block is the count obtained for that combination, 

 and the number in parentheses below is the approximate percentage of 

 that count in the total sample] 



DORSAL SOFT-RAYS 



CO 



< 





Anal soft-rays. — 16 or 17 (table 21). Ginsburg 

 (1952: 93) and Nichols and Roemhild (1946, 

 fig. 1) gave a range of 15 to 17. The figure of 



