PLATE XLIV. 



Figure 1. Cidaris opipara, Duncan and Slaiien (page 279) . Abactinal view of the test, natural size. 



2. Profile view of the same test, natural size. 



3. Actinal view of a smaller specimen, natural size. 



4. Ambulacral plates near the amhitus, from the same specimen as Fig. 1, magnified. 



5. Ambulacral plates on the abactinal part of the area, from the same specimen, magnified. 



6. Interambulacral plate, from the same specimen, magnified. 



7. Portion of an ambulacral area, to show the flexure and the posture of the plates, from the 



same specimen as Fig. 3, magnified. (Inadvertently placed upside down by the artist.) 



8. Portion of the margin of the peristome, from the same specimen, magnified. 



9. Cidaris excelsa, Duncan and Sladen (page 282) . Interambulacral plate, magnified. 



10. Ambulacral plates, magnified. 



11. A fragment of the test, natural size. 



