PLATE IV. 



Figure 1. Linthia Sindensis^ Duncan and Sladen (page 18). Abactinal aspect of the test, 

 natural size. 



2. Longitudinal profile of the same, natural size. 



3. Transverse profile of the same, showing the posterior extremity, natural size. 



4. Outline of the transverse profile of the test, natural size. 



5. Apical system, magnified. 



6. Apical extremity of the odd anterior ambulacrum, more highly magnified. 



7. Portion of the test, showing the passage of the peripetalous fasciole near the extremity 



of a petal, magnified. 



8. Portion of the test, showing the ornamentation near the lateral fasciole, magnified. 



9. One of the large tubercles on the actinal surface, magnified. 



10. Tubercles of the abactinal surface, magnified. 



11. Profile view of the same, magnified. 



