EXPLANATION OF PLATE LVIL 

 ECHINOIDEA. 



Chcetodiadema tuberculatum.. 



Fig. 1. — Actinal view of an interambulacrura and an ambulacrum; 



natural size. 

 Fig. 2. — A "claviform pedicellaria." x 70. 

 Fig. 3. — A triphyllous pedicellaria. x 70. 

 Fig. 4. — Valve of a triphyllous pedicellaria. x 70. 

 Fig 5. — A tridentate pedicellaria. x 70. 

 Fig. 6. — Valve of same, x 70. 

 Fig. 7. — Same as fig. 6, seen from side, x 70. 

 Fig. 8. — A very large pedicellaria, incompletely developed x 70. 



