in; 



KOSSIL ASTKROIDEA. 



2. Spine-pits shallow, circular, circles variable in size, adjoining. 



One species, C. latum. Text-fig. 10. 



Text-fig. 10. 



3. Spine-pits deep, circular, not adjoining. 



Text-pig. 11. Text-fig. 12. 



a. Spine-pits coarse. N. marginatus. Text-fig. 11. 



b. Spine-pits fine, not on margin. N. oligoplax. Text-fig. 12. 



' 



c. Spine-pits fine, uniformly over the whole of plate. P. lunatus. 



Text-fig. 13. 



Text-fig. 13. 



4. Spine-pits on outer edge of plate with raised margins. 



9 , 



f frf 



§11 



Text-fig. 14. 



One species, P. quinqueloba (see p. 108). Text-fig. 14. 



