PLATE LXXVII. 



Page 

 DicHOCRixus POLTDACTYLua Cass. and Lyon 756 



la. A large specimen with arms. 



lb. Posterior view of calyx, showing the elevated dome and disk ambulacra. 



DiCHOCRIXUS LACHETMOSUS Hall 754 



2a. Specimen with arms and stem. 

 2b. Posterior view of calyx. 

 2c. Ventral aspect of same. 



DiOHOCKINUS LIRATUS Hall 759 



3a. Specimen showing the arms and stem. 

 3b. Posterior view of the dorsal cup. 



DicHOCRiNus ciNCTUs Miller and Gurley 764 



4a. Posterior view of specimen with arms. 

 ib. Ventral aspect of the calyx. 

 4:C. Distal face of first distichal (f). 



DiCHOCEINUS PLICATUS Hall 758 



5a. A small specimen with arms and stem. 



5b. Another specimen, giving a side view of the dorsal cup. 



DiCHOCEINUS OENATus W. and Sp 7G2 



6. Specimen with arms and stem, from near Mt. Pleasant, Iowa. 



DiCHOCEINUS L^vis Hall 765 



7a. Specimen with arms. (Coll. Mr. Fultz of Burlington.) 



7b. Another specimen. (Same collection.) 



7c. Portion of an arm with pinnules (enlarged). 



DiCHOCEINUS ovATUs 0. and Sh 760 



8a. A specimen with arms. 



8b. Posterior view of the dorsal cup. 



DiCHOCEINUS OBLONGUs W. and Sp 759 



9. Posterior view of the type specimen. 



