442 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Figure 32. — Ventro-dorsal view of head of cleared and 

 stained 8.2-mm. Mullus auratus showing position of 

 branchiostegal rays. Line equals 1 mm. 



expressed in tx)tal lengths. In the 8.2-mm. M. 

 auratns, the position of the first ray was more 

 anterior relative to the eyes and point of fusion 

 of the branchiostegal membrane than in Lo Bi- 

 anco's specimen; in these respects it conformed 

 most closely with his illustration of a 22-mm. 

 Mullus (Lo Bianco, 1907). 



Two 19-mm. stained specimens of M. auratus 

 showed the first branchiostegal rays displaced as 

 far forward as the anterior edge of the eye. They 

 still retained the same general shape as tlie other 

 branchiostegal rays and were separated from each 

 other by a distance of 0.3 mm. at their closest point. 



Barbel length was 2.3 mm. on one specimen and 2.6 

 mm. on the other. Three of the four barbels on the 

 two specimens had detached from the branchioste- 

 gal membrane. Lo Bianco noted that this separa- 

 tion from the membrane occurred between 26 

 and 30 imn. in his series of Mullus. In M. auratus, 

 one of the barbels was detached in a fish as small 

 as 9 mm. ; the barbel at this size measured less than 

 2 mm. One 14.5-mm. specimen had both barbels 

 free. On the other hand, a 2J:.5-mm. specimen had 

 one barbel still attached to the membrane. This 

 is the largest specimen in which any barbel re- 

 mained attached, and all of the specimens between 

 14.5 mm and 24.5 mm. had at least one barbel free. 

 At 28 mm. the bases of the barbels had shifted 

 forward past the posterior edge of the mouth, and 

 the anterior ends of the bases had joined together. 



Operculum 



The opercular bone (fig. 33) did not possess a 

 spine on any specimen examined, and the pos- 

 terior edge is rounded and smooth. 



Figure 33. — Operculum and cleithrum of 44.9-mm. Mul- 

 lus auratus. Line equals 2 mm. 



Cleithrum 



This small inconspicuous bone (fig. 33), almost 

 covered by the opercular flap, had no serrat ions as 

 it does in P. maculatu^. 



