PLATE LXXVI. 



Page 



AetheacanthA ithacensis Williams 749 



Fig. la. Lateral view of a specimen with. arms. (Museum Cornell University.) 

 16. Basal disk. 

 lc. The movable spines upon the tegmen. 



Abtheacantha punctobeachiata Williams 750 



2a. Specimen showing spine bases. (Coll. W. and Sp.) 



2b. Another specimen with some spines attached. (Coll. Prof. S. Calvin.) 



Abtheacantha depeessa W. and Sp 751 



3a. Dorsal aspect of the type specimen. (Coll. W. and Sp.) 

 3b. Ventral aspect of the same specimen. 



Dichoceinus lineatus Meek and Worthen 761 



4a. The type specimen ; posterior view of the calyx. (Mus. Comp. Zool.) 

 Ab. Anterior view of the same specimen. 

 4c. Dorsal aspect of same. 



Dichoceinus pisum Meek and Worthen 763 



5. Specimen with arms. (Mus. Comp. Zool.) 



Dichoceinus ceassitestus White 769 



6a. The type specimen ; the anterior side exposed. (Same collection.) 



6b. Another specimen with part of the column attached. (Coll. W. and Sp.) 



6c. Posterior view of the calyx and anal tube. (Same collection.) 



Dichoceinus ovatus Owen and Shumard 760 



7. A fine specimen with arms. (Mus. Comp. Zool.) 



Dichoceinus lieatus Hall 759 



8. Specimen with arms and part of column. (Same collection.) . 



Dichoceinus coxanus Worthen 763 



9. The type specimen. (Coll. L. A. Cox.) 



Dichoceinus hamiltonensis Worthen 772 



10. The type specimen. (Same collection.) 



