224 



FOOT-NOTES TO EVOLUTION. 



in common that the coral reefs, rocky islands, and tide 

 pools of the tropics have not ? 



FIG. 16. Skeleton of the spotted greenling (Hexagrammos dccagram- 

 mus). From nature, by W. S. Atkinson. A northern fish, with 

 vertebrae numerous and small. 



In this connection we are to remember that the fewer 

 vertebrae indicates generally the higher rank. When 



vertebras are few in number, as a rule 

 Fewer vertebrae eacn Qne j g i ar or er> j ts structure is more 

 indicates greater .... . . 



specialization. complicated, its appendages are larger 



and more useful, and the fins with which 

 it is connected are better developed. In other words, 

 the tropical fish is more intensely and compactly a fish, 



FIG. 17. Skeleton of the scarlet rock-fish (Sebastodes mttiiatus). From 

 nature, by W. S. Atkinson. A species of temperate waters ; the 

 vertebrae in moderate number. 



with a better fish equipment, and in all ways better fitted 

 for the business of a fish, especially for that of a fish that 

 stays at home. 



