PLATE 139. 



N.B. — The signification of the characters is the same in all the figures (compare p. 718). 



a. Northern polar spines. 



b. Northern tropical spines. 



c. Equatorial spines. 



d. Southern tropical spines. 



e. Southern polar spines. 



Belonaspida et Hexalaspida. 



Fig. 1. Hexacolpus nivalis, n. sp., . 



Fig. 2. Hexalaspis heliodiscus, n. sp., 



Fig. 3. Hexaconus ciliatus, n. sp., . 



Fig. 4. Hexaconus serratus, n. sp., 



c, Central base of an equatorial spine ; d, central 



Fig. 5. Hexaconus coronatus, n. sp., 

 Fig. 6. Hexaconus velatus, n. sp., 



Marginal view of the shell. 

 Fig. 7. Hexaconus vaginatus, n. sp., 

 Fig. 8. Thoracaspis bipennis, n. sp., 

 Fig. 9. Belonaspis datura, n. sp., 



of a tropical spine. 



Diam. Page 



x 300 880 



x 300 875 



x 300 876 



x 300 877 



x 300 877 



x 300 877 



x 300 877 



x 300 862 



x 400 863 



