2 



Page 

 Fig. 15. The upper portion of a radial sinus, showing the anibulacral opening between two 



deltoid plates. x 6 51 



Fig. 16. Interradial view of a young individual. x2 241 



Schizoblastus Sayi, O. fy S., sp., p. 224. 

 Fig. 17. Terminal portion of an ambulacrum, with the lancet-plate exposed in the middle 

 line, and some of the side plates in position, the others having been removed. 

 Subcarboniferous, Iowa. Coll. Wachsmuth. x 6 57 



Ph^noschisma Verneuili, E. i$ C, p. 273. 



Fig. 18. Summit view, with the ambulacra removed, and the hydrospire-slits exposed on the 



sides of the radial sinuses. Lower Devonian, Asturias. x 4 273 



Codaster alternatus, Lyon, var. elongatus, Wachsmuth, var. 



Fig. 19. Summit view of an imperfect specimen, showing the ambulacra and the radio- 

 deltoid sutures crossing the hydrospire-slits. Lower Devonian, Kentucky. Coll. 

 Wachsmuth. x 4 33 



Fig. 20. Interradial view of the same specimen, broken below. x 3 33 



