PLATE VI. 



POTERIOCRINUS MAGNIVENTRUS, Sp. nOV. 



Fig. 1. Lateral view of calyx and lower part of arms, showing the strong, short pinnules, 

 and plated skin of tegmen at base of sac. Coll. Yale l^niversity Museum. 



2. Left lateral view of mature specimen with stem and arms attached, and remnants 



of ventral sac towards upper end; Platyccras in position with mouth toward 

 anterior side: shows full height of IHB, with abnormally some small plates 

 interposed iJetween them and BB; folds of plates smooth on the raised parts. 



3. Young specimen with stem, part of arms, and sac, lateral view. Note the sharp 



ornamentation of plates on the raised ridges, contrasted with the same parts 

 in last specimen. 



Marsupites americanus, sp. nov. 

 Upper Cretaceous. Plymouth Bluff, Mississippi. 



Fig. 4a. Lateral view of calyx, with bases of arms, and a strong interbrachial passing in 

 between them. Coll. Frederick Braun. 

 Ah. Bas<d view of same, showing the large centrale within the ring of IBB. 

 5. An infrabasal plate of a much larger specimen. 



