318 THE AMERICAN NATURALIST [Vol.L 



and had died, from time to time, in the laboratory aquaria. The 

 mid-dorsal ridge is indicated in the figures by the dotted line. 



Only the black-bordered vermilion spots were noted, the small 

 black spots being too numerous and irregular to make it worth 

 while to study them. 



It will be noticed that in the animals from Woods Hole, shown 

 in figures 21 to 24, the red spots were much smaller than most of 



