zones where the difference between the fresh- 

 water and ocean type circuli is not clear. See 

 plate 6. 



Interciradus space, intersvace. — A groove be- 

 tween two circuli. See circuli. 



Intermediate groivth, intermediate zone, inter- 

 mediate growth zone. — See incidental growth 

 zone. 



Interspace. — See intercirculus space. 



Lacustrine growth, lacustrine zone, lacustrine 

 groivth zone. — See fresh-water growth. 



Marine growth, marine zone, marine growth 

 zone, ocean growth*, ocean zone, or ocean groivth 

 zone. — The portion of the scale formed while the 

 fish was in the ocean. See plates 1 and 7 through 

 11. 



Migration check. — An adventitious check 

 formed on some scales at the end of the incidental 

 or plus gi'ou'th. See plate 6. 



Nucleus. — See fresh-water growth. 



Ocean groivth*, ocean zone, ocean groivth zone. 

 — See marine growth. 



Plus growth*, plus zone, plus growth zone. — 

 See incidental gi'owth. 



Posterior field* or area. — See clear field. 



Regenerated scale. — A scale that replaces one 

 that has been lost. The new scale grows without 

 the formation of circuli until it reaches the ap- 

 proximate size of the scale which was lost. See 

 plate 17. 



Resorbed* or eroded scale. — A scale with the 

 margins eroded because of sexual maturation. 

 See plate 18. 



Resting zone. — See annual ring. This term is 

 often used by Japanese scientists. 



Scar. — An abrupt change in the regular pat- 

 tern of scale gi'o\\i;h marked by a displacement 

 of the natural configuration of the circuli. See 

 plate 19C. 



Sclerite. — See circulus. This term is widely 

 used in Europe. 



Sculptured field or area.- — See anterior field. 



Spring growth or spring growth zone. — See 

 incidental growth and footnote 8. 



Stria. — See circulus. 



Transition zone, transitional growth, transi- 

 tional groxoth zone, transition zone. — See inci- 

 dental growth. 



Winter ring, winter mark, or winter zone*. — 

 See annual ring. 



Year mark or year ring. — See annual ring. 



APPENDIX B 



EFFECT OF MAGNIFICATION ON APPEARANCE 

 OF SCALE FEATURES (Appendix Plate 1) 



The magnification which should be used for 

 examination of scales from sockeye salmon var- 

 ies with the size of the scales, the intended use 

 of the data, and the preference of the scientist. 

 The photogi'aphs in appendix plate 1 show how 

 features of sockeye salmon scales appear at dif- 

 ferent magnifications and indicate the relative 

 magnifications for various scale studies. (The 

 arrows indicate the same feature on each scale 

 section.) 



Scale sections (shown at various magnifica- 

 tion) follow: 



Section A. About 19 X. Note how difficult it is 

 to identify any of the scale features 

 on this photograph. 



Section B. About 25 X. Note that the ocean 

 winter zones are distinct at this 

 magnification, but the fresh-water 

 features are difficult to determine. 



Section C. About 50 X. The ocean winter 

 zones are less distinct at this mag- 

 nification, but the details of the 

 fresh-water zone are clear. 



Section D. About 100 X. The ocean winter 

 zones are very difficult to identify 

 and delimit at this magnification. 



Thus, the scales should be studied first at a 

 magnification of between 25 X and 50 X to ob- 

 serve the whole scale in perspective and the de- 

 tails of the ocean zone. Then a magnification of 

 between 50 X and 100 X should be used for the 

 fresh-water zone, counts, and measurements of 

 circuli, . . . These, ranges of magnification are 

 suggested as a starting point, because the exact 

 magnification needed depends on the use of the 

 data and on the temperament and visual habits 

 of the investigator. 



276 



U.S. FISH AND WILDLIFE SERVICE 



