SHORT BIGEYE IN WESTERN NORTH ATLANTIC 



125 



BODY PROPORTIONS 



Twenty-five body parts were measured on a 

 complete sLze range of specimens from the largest 

 larva (6.6 mm.) Jo the largest adult (261.8 mm.) 

 and the data presented in table A-1. Selected 

 measurements were made on 158 additional speci- 

 mens from the smallest larva (2.2 mm.) to a 254.9- 

 mm. individual (table A-1). These measurements 

 were plotted relative to standard length, and the 

 resulting scatter diagrams are included in figures 

 3 and 25 to 32. Regression lines were eye-fitted 

 to the data with a straight-edge for discussion pur- 

 poses, but were not included in the figures. All 

 proportions of larvae were not measured because 

 most of the characters included here are based on 

 parts not present in larvae or because the larvae 

 are so unlike the prejuveniles that to include them 

 would be of little value. The larvae are illustrated 

 in figures 8 to 10. 



The distances from pelvic-fin insertion to snout 

 and to midcaudal base were not measured, as 

 the insertion of this fin remained constant in 

 position with that of the pectoral. 



Eye diameter in relation to head length and 

 to standard length was discussed in detail in 

 an earlier section on metamorphosis in relation 

 to change of habitat. The eye diameter initially 

 has a higher rate of increase than in sizes greater 

 than about 35-65 mm., the zone of transformation 

 (fig. 3). The relation of eye to head remains 

 constant at all sizes, after an upward step at 

 metamorphosis (fig. 4). 



Figure 11. — Pelagic prejuvenile Psemhpriacnnthus alius, 

 12.1 mm. standard length (BLBG, Gill Cr. 7, Reg. 38). 



Figure 12. — Pelagic prejuvenile Pseudopriacanthus alius, 

 15.0 mm. standard length (BLBG, Gill Cr. 8, Reg. 54). 



Many of the regression lines eye-fitted to the 

 body proportions in standard length show inflec- 

 tions at various sizes (step indicated in paren- 

 theses) ; some show no inflection. The body pro- 

 portions are as follows : 



Body depth at pelvic-spine base, down (75- 

 85 mm.), figure 25; body depth at third anal-spine 

 base, down (75-85 mm.), figure 25; head, down 

 (125-135 mm.), figure 32; snout to doi-sal-fin ori- 

 gin, down (120-130 mm.), figure 30; snout to 

 dorsal-fin termination, down (75-85 mm.), figure 

 30; snout to anal-fin origin, no inflection, figure 

 30; postorbital, down (80-90 mm.), figure 32; 

 least depth of caudal peduncle, down (150-160 

 mm.), figure 29; dorsal -fin origin to midcaudal 

 base, down (95-105 mm.), figure 29; anal-fin origin 

 to midcaudal base, down (95-105 mm.), figure 29; 

 dorsal-fin base, down (65-75 mm.), figure 32; 

 anal-fin base, down (80-90 mm.), figure 32; bony 

 interorbital, down (50-60 mm.), figure 31; pec- 

 toral fin origin to snout, down (110-120 mm.), 

 figure 31 ; pectoral fin length, do\vn (95-105 mm.), 

 figure 31; pelvic-fin sphie length, down (150-160 

 mm.), figure 28; second pelvic-fin soft-ray length, 

 down (100-120 mm.), figure 28; maxillary, down 

 (120-130 ram.), figure 30; third doi-sal-fin soft- 

 ray, down (step at 70-80 mm.), figure 27; third 

 anal-fin soft-ray, down (70-80 mm.), figure 27: 

 snout, up (50-60 mm.), figure 30; dorsal-fin termi- 

 nation to midcaudal base, up (110-130 mm.),^ 

 figure 26; anal-fin termination to midcaudal base, 

 up (110-130 nun.), figure 26; and pectoral fin 



