? 



Plate 23. 

 1-13. Dialithocidaris gemmifera A. Ag. ; Station 3382. 



1. Actinal system of specimen measuring 21 mm. in diameter. 



2. Abactiual system of same as fig. 1. 



3. Tlie same specimen as fig. 1, seen facing the left anterior interambulacrum. 



4. Actinal part of odd anterior ambulacrum of same. 



5. Actinal [nirt of odd anterior ambulacrum, showing the auricles, seen from the exterior. 



G. Actinal part of the left posterior interambulacrum and ambulacrum, seen from the 

 interior. 



7. One of the pores at the actinostome. 



8. The tenth pore from the actinostome. 

 1). Ambulacial pore close to the ocular plate. 



10. Eye-plate of the left posterior ambulacrum, seen from the interior. 



11. Embryonic tubercles of the left anterior interambulacrum. 



12. Primary tubercle, third plate from the actinostome, of the left posterior interambolfr 



crum. 



13. P)ase of primary radiolc. 



