Explanation of Plate I 



Cassidulus intermedius sp. nov., page 6. 



Figs. 1-4. Dorsal, ventral, posterior and lateral views of the type specimen. 

 Xi. 



Fig. 5. Portion of the left posterior ambulacral area at base of the petaloid 

 region, greatly enlarged. 



Fig. 6. Right posterior phyllode with the adjoining bourrelets, greatly 

 enlarged. 



Cassidulus hemisphericus sp. nov., page 7. 



Figs. 7, 8. Dorsal and lateral views of the type specimen. Xi. 



Fig. 9. Portion of the anterior ambulacral area at the base of the petaloid 

 region, greatly enlarged. 



