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Pteeotoceinus ceassus Meek aud Worthen 801 



Fig. 8. Posterior view of the type specimen. (After Meek and Worthen.) 



Ptebotoceinus acutus, var. bifuecatus Wetherby 801 



da. Dorsal aspect of the type specimen. (After Wetherby.) 



%. Ventral aspect of the same. 



10. Diagram, showing the arrangement of the lower brachials in Pterotocrinus. 



