SHORT BIGEYE IN WESTERN NORTH ATLANTIC 



123 



Gill Rakers 



The smallest specimen in which gill rakers were 

 counted was 19.9 mm. The count obtained, 

 8 + 19, falls at the mode of the range for the adults. 

 Variation in combinations of upper-limb and 

 lower-limb gill rakers is summarized in table 6. 



Although the size at which gill rakers first form 

 was not determined, they were well-developed in 

 the smallest prejuvenile of 8.2 mm. 



Table 6. — Variation in upper- and lower-limb gill-raker 

 counts for 112 specimens of Pseudopriacanthus altus 



(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] 



UPPER LIMB 



o 



.J 



Bony Cranial Crest 



A single prominent, medial, cranial crest, 

 armed throughout its length with 8 strong dorso- 

 medial serrations, and with a sharply upturned 

 (about 40°) backward projection, was present on 

 a 2.2-mm. individual (fig. 8). At 2.4 mm., the 

 serrations had increased in number and become 

 less prominent, while the backward projection 

 had begun to decrease its angle and lie flatter 

 against the head and body. By 2.6 mm., the 

 serrations were lost on the anterior part of the 

 crest and were weak on the backward projection 



Figure 8. — Larval Pseudopriacanthus altus, 2.2 mm. 

 •Stat dud length (BLBG, Gill Cr. 3, Reg. 1), Semi- 

 diagrammatic. 



620220 0—62 4 



Figure 9. — Larval Pseudopriacanthus altus, 3.2 mm. 

 standard length (BLBG, Gill Cr. 3, Reg. 75). Semi- 

 diagrammatic. 



(which by this size was flat against the dorsal sur- 

 face of the body except for its still-upturned tip). 

 At 3.2 mm. (fig. 9), a small, weakly serrate, sec- 

 ondary crest had appeared on the anterior median 

 surface of the original crest. A compressed sec- 

 ondary crest also had formed at the angle made 

 by the upturned projection. By 6.6 mm. (fig. 10) 

 this crest had expanded to include the entire 

 length of the original crest. Strong serrations, 

 each supported by a thickening to the foundation 

 formed by the original crest, extended along the 

 top of this secondary crest (fig. 10). By 8.2 mm., 



Figure 10. — Larval Pseudopriacanthus altus, 6.6 mm. 

 standard length (BLBG, Gill Cr. 3, Reg. 49). Semi- 

 diagrammatic. 



the serrations had become weaker, and the entire 

 crest had begun to be absorbed by overgrowth of 

 the dorsal surface of the head. Only a row of 

 weak serrations in the midline of tlie forehead re- 

 mained in a 16.8-mm. specimen, an outline only 

 by 19.9 mm., and all trace had disappeared in a 

 34.0-mm. individual. 



Supraocular Crest 



Larval and early prejuvenile F. alius possess an 

 evebrowlike serrate bonv crest over each eve. 



