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Fishery Bulletin 94(2), 1996 



statolith was reheated to soften the medium and 

 turned over with a pair of probes constructed of in- 

 sect pins so that the anterior face could be ground 

 (Fig. 2, C (2) and D). The statolith was oriented with 

 the dorsal dome elevated and the anterior face was 

 carefully ground. When the nucleus was clearly re- 

 vealed, the anterior face was polished and cleaned. 

 Because the statolith of L. pealei grows outward 

 from the oval-shaped nucleus in a curved manner 

 (Fig. 2, A and B), a second grinding and polishing of 

 the posterior surface (Fig. 2E i was generally needed 

 to reveal the entire sequence of growth increments 

 from the nucleus to the lateral dome (LD) margin. 

 Because of this curvature, no single sectioning plane 

 could have exposed all layers equally well. As a re- 

 sult, the use of the typical two-sided grinding method 



(Jackson, 1990a; Jereb et al., 1991) would have pro- 

 duced increments that were difficult to resolve. To 

 circumvent this difficulty, the posterior surface was 

 ground a second time (Fig. 2E) at a slightly different 

 angle to approximate the curved statolith growth 

 plane. For squid smaller than 2 cm ML, however, a 

 single grinding of each surface was usually sufficient 

 to reveal the statolith microstructure. After the sec- 

 ond posterior grinding, the mounted statolith was 

 reheated, and a thin film of fluid medium was 

 smeared over the uppermost ground surface to im- 

 prove transparency. As the medium cooled, the LD 

 margin was elevated so that the last-ground plane 

 was approximately parallel to the surface of the slide 

 (Fig. 2F); this was done to improve the clarity of sta- 

 tolith microstructure under a 40x objective lens. 



