The relations between the hybrid and parent forms of echinoid larvæ

The object of this research was to determine systematically during a period of several months’ duration,the exact relationship of structure and size existing between certain hybrid and parent Echinoid larval forms. Eight different species of Echinoids were worked with, but the larger number of observations were confined to three of them viz.,Strongylocentrotus lividus ,Sphœrechinus granularis andEchinus microtuberculatus . The method of procedure was similar to that described in a former paper.