6l8 PHYLUM CHORD ATA : CLASS PISCES— FISHES 



Each centrum in the trunk region bears superior neural 

 processes, uniting in a neural arch crowned by a neural 



ANTERIOR END 



SUMMER -^i - - 



SMALL 4> „ 



SUMMER ^i -- 



GRILSE 



VERY 

 6YRS. — LARGE 

 SPRING 



— LARGE 

 SPRIN* 



< _ SMALL 

 U SPRING 



in 



— SNOLT 

 1 



EXPOSED OR POSTERIOR EMD OF SCALE 



Fig. 352. — Lines of growth on salmon's scale. — 

 From J. Arthur Hutton. 



A broad zone represents a summer's growth ; a narrow zone represents 

 a winter's growth or practical cessation of growth. 



Fig. 353. — Diagram showing the zigzag, somewhat W-shaped muscle- 

 segments or myotomes, separated from one another by delicate 

 connective tissue. Shape and dovetailing may be interpreted 

 as adaptations to the locomotor bending of the body from side 



to side. 



L.L., The sensory lateral line. 



spine, and transverse processes projecting from each side. 

 Articulated to the distal ends of the transverse processes 



