BY THE SAME AUTHOR. 



Jelly -Fish, Star -Fish, and Sea -Urchins. 

 Being a Research on Primitive Nervous Sys- 

 tems. i2mo, cloth, $1.75. (International 

 Scientific Series.) 



Animal Intelligence. i2mo, cloth, $1.75. (In- 

 ternational Scientific Series.) 



Mental Evolution in Animals. With a Post- 

 humous Essay on Instinct by Charles Dar- 

 win, F. R. S. i2mo, cloth, $2.00. 

 D. Appleton and Company, Publishers, New York. 



