104 



FISHES 



Figure 105. — Perch. 



Amphioxus (am-fi-oks'us), the notochord persists and 

 there is never a true backbone. The notochord is always 

 found above the food tube and below the spinal cord. 



Another characteristic common to all vertebrates is 

 the presence of gill-slits. These are external openings on 



Figure 106. — Sunfish or Pumpkin Seed. 



