124 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



33 mm., the largest yellowfin examined, the color 

 pattern follows closely the description published 

 by Schaefer and Marr (1948b). 



A 12-mm. yellowfin displays three prominent 

 spines at the angle of the preoperculum. Anterior 

 to these are thi'ee lesser spines, and thiee others 

 protrude from the preoperculum above the lai'ge 

 spines. With increasing length of fish, all spines 

 become more and more reduced in relation to the 

 size of the head. They are apparently overgrown 

 by the superficial layers of the preopercular bone. 

 In fish of 26 mm., the only spines discernible are 

 those at the angle of the preoperculum, and even 

 these are noticeably less evident. There appears 

 to be little, if any, growth in these spines over the 

 size range of the fish in my collections. 



AUXIS THAZARD (Lacepede) 



This species is the most numerous in the night 

 collections. Young stages are present in 12 of the 

 14 collections. The 157 specimens taken range 

 from 10 to 49 mm. in length. In addition to the 

 collections listed in table 1, two larger Auxis, 79 

 and 117 mm. fork length, were taken from the 

 stomach of a large yellowfin caught on May 6 at 

 11°40' N. latitude, 91°00' W. longitude. These 



two fish, both broken and with the skin and fins 

 digested away, can be recognized as members of 

 the genus Auxis by the elongated right lobe of the 

 liver, the total vertebral count (39), and the struc- 

 ture of the individual vertebrae as described by 

 Kishinouye (1923: 460). The gill-raker counts,^ 

 10-f- 1-1-32 and lO-f- 14-33, approximate the counts 

 made by Schaefer and Marr (1948a) on most of 

 their juveniles. In a recent paper. Wade (1949) 

 separates the Philippine species, Auxis (hazard 

 and A. tapeinosoma, on the basis of characters 

 among which only the gill-raker count is apphcable 

 to the young stages.^ He also points out, as 

 Schaefer and Marr (1948a) suggested, that there 

 are probably two species of Auxis in Central Amer- 

 ican waters. If we assume that there are two 

 species and that they can be separated by charac- 

 ters applicable to the Philippine species, my two 

 juveniles, as well as the postlarvae large enough to 

 show a definitive gill-raker count, are A. thazard. 

 The giU-raker counts of 10 specimens are given in 



2 The method used in counting and recording gill rakers is the same as that 

 used by Wade (1949) in his discussion of the genus Auih. 



3 Wade's description of Anns tapeinosoma agrees with that of Bleeker 

 (1854). However, the pattern and extent of the corselet scales in Bleeker's 

 figure (18M, pi. 7) of A. tapeinosoma agrees more closely with Wade's figure of 

 A. thazard. 



Figure 2. — Aiais thazard, 11.5 millimeters long. 



Figure 3. — Attxis thazard, 18 millimeters long. 



