LIST OF ILLUSTRATIONS IN THE TEXT. 
Pago 
1. Transverse sections of the Pentacrinine Stern. Outline diagrams, a — li . 
2. Internodals of the Pentacrinine Stern. Outline diagrams, a — f . 
3. Diagram of three sectors of the joint-face of a Pentacrinine internodal, showing different types 
of development and the terms applied thereto. 
4. The diameters of a cylindrical and of a stellate columnal contrasted. 
5. Axial nerves and vessels in an intersyzygium of Isocrinus candelabrum. A, joint-face of the 
hypozygal, X 15 diam. V, central portion of the ground section of the epizygal, x 65 diam. 
6. General orientation of Echinoid ambulacra and interambulacra. 
7. Diagram showing the normal direction of imbrication in Echinoid ambulacrals and mterambu- 
lacrals . 
8. Diagram illustrating Terminology of Echinoid interambulacrals and ambulacrals. 
9. The Terminology of a main Tubercle, illustrated by a transverse section. 
10. Diagram to show relations of ambulacrals to interambulacrals in Triadocidaris persimilis, 
X 36 diam. 
11. Three diagrams showing Terminology of primary Radioles. 
12. Anaulocidaris testudo: Radioli remiformes (a — k) . 
13. » » Radioli spatuliformes (a—e) . 
14. » » » » (/—j \ . 
15. » » » » (Ji — o). 
16. » » » » ( p — s ) . 
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Anaulocidaris 
Buchi 
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two views of a trulliform radiole. .... 
two diagrams of a trulliform radiole, to show direction of lines of 
Ornament. 
Radioli trulliformes (a — d) . 
» ( e — h) . 
» » (i—J) . 
» » (m — p) . 
» '> [q— s). 
Radioli paletiformes (a, c, e, li) . 
(j, 1, in, o ). 
» ( p, q, r, n, v) . ... 
Radiolus remiformis <MM a) . 
(MM b) . 
(MM c) . 
» » (RAW n). 
(HMW a) . 
» (HMW b) . 
(HMW c) . 
» » (BM a ). 
» » (BM b) . 
» » (BM c) . 
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