IIG 



FOSSIL ASTEROIDEA. 



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



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



Text-fiq. 10. 



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



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



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



Text-fjo. 11. Text-fig. 12. 



c. Sprue-pits fine, uuiforruly over tlie vliole of plate. P. lunatus. 

 Text-fig. 13. 



Text-fio. 13. 



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



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



Text-pio. \l. 



