Plate 54. 



1-3. Habrocidaris argentea A. Ag. and CI. 



1. Actinal view of denuded test, x 4. 



2. Abactinal view of same, x 4. 



3. Right anterior interambulacrum. x 4. 



4-9. Habrocidaris scutata A. Ag. and CI. 



4. Actinal view of denuded test. X 3. 



5. Abactinal view of same. X 3. 



6. Side view of same, showing left anterior ambulacrum. X 3. 



7. Left anterior interambulacrum. x 3. 



8. Part of primary spine, x 6. 



9. Cross-section of spine. X 8. 



