ON THE EXPERIMENTAL HYBRIDIZATION OF ECHINOIDS. 



293 



5. A^ X Ec/ 



36 \\ l[ 37 II fl 38 1^;^ SQ \[; j 40 



Text-fig. 5. — 40 camera drawings of the apical ends of the larval skeleton of E. acutus f x E. cscukntus (J . 



