Plate 111. 



From specimens in tiie author's collection, unless otherwise stated. 



1. Cidaroblastiis grannlaris, — loaned by G. K. Green. 



2. Lateral view of same species, — Troost Collection, Smithsonian Institu- 

 tion, No. 33080. 



3. Summit view of same. 



4. Cidaroblastus glohosus, — Troost Collection, Smithsonian Institution^ 

 No. 38077. 



5. Globoblastus magnificus. 



6. 7. Lateral and basal views of Pentremites sulcatus, showing an elongated 

 piece inserted between two fork pieces. 



8, 9. Pentremites pyriformis, showing an undeveloped fork piece and 

 ambulacrum. 



10. Pentremites sidcatus, showing a crippled ambulacrum. 



11, 12. Pentremites sulcatus, with only four ambulacra developed and a 

 fifth fork piece solid. 



13, 14. Pentremites snlcatus, with only four ambulacra. 

 15, 16. Pentremites pyriformis, with six fork pieces but only four ambu- 

 lacra developed. 



17. Saccoblastus, with live fork pieces but six ambulacra, of which two 

 occupy one sinus. 



18. Pentremites godoni, with four fork pieces but with five ambulacra, of 

 which two occupy one sinus. 



