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Fishery Bulletin 9 1 (4), 1993 



dium was completely enclosed. This determination is 

 based on sagittal sections at the level of the central 

 primordium. 



Unenclosed peripheral area 



Otoliths of all Stage 3-5 larvae had 

 at least two accessory primordia ( AP), 

 when viewed in sagittal section ( Fig. 

 8, A-D). A maximum of seven AP 

 were observed, although additional 

 AP on the lateral surface of the otolith 

 (Fig. 9) were obscured when otoliths 

 were prepared in sagittal section. Ac- 

 cessory primordia always formed ad- 

 jacent to growth from the central pri- 

 mordium, rather than adjacent to 

 growth from previously formed AP. 

 On right otoliths, AP were easier to 

 discern than on left otoliths, possibly 

 because the plane of growth changes 

 at about the time of AP formation in 

 left, but not right, otoliths (Fig. 10, 

 A and B). Increments emanating 

 from AP exhibited higher contrast 

 and were wider (about 3.0pm) than 

 those emanating from the central 

 primordium. 



The most anterior AP appeared 

 to form first and was closely associ- 



ated with the transition from clear to opaque central 

 areas. However, the exact origin of the anterior AP 

 was usually impossible to discern because it merged 



/ 



Figure 7 



Sagitta from 51.5 mm Stage-1 Dover sole. Microstomas pacificus, larva collected on 

 12 July 1991 near Destruction Island. Washington. Anterior and posterior cavities 

 are indicated by arrows. The lateral face of the otolith (surface toward viewer) has 

 been ground to the level of the central primordium; the medial face has been left 

 intact. Estimated number of increments was 229 (Table 3). Magnification = 400x. 



