542 THE CRINOIDEA CAMEEATA OF NORTH AilEEICA. 



Megistocrinus multidecoratus (Baeeis). 

 FMe XLIX. Fig. 6. 



18S5. Megistocrinus iiodosus, yax. multiiecoratits — Babkis; Proceed. Daveup. Acad. Nat. Sci., Vol. IV. 



p. 100, Plate ir., rigs. 3 aud i. 

 1885. W. and Sp. ; Revision Palaiocr., Part III., p. 113. 



This species agree.? in the general form and the arrangement of the 

 plates closely with M. nodosus, but differs essentially in the extent and char- 

 acter of its ornamentation. The plates, instead of having a single central 

 node, are covered by series of nodes, and these are not restricted to a few 

 Ijlates as in that species, but cover every plate of the calyx. The nodes are 

 as a rule well defined, but of irregular size and without definite arrangement, 

 and they vary in number in different plates ; the radials, costals, and first 

 interbrachials have from five to twelve, which are arranged in rows ; while 

 the higher brachials seldom have more than two or three at the most. The 

 l^lates of the tegmen are also highly ornamented, each one bearing a central 

 node, from which rows of smaller nodes radiate to the angles. It may be 

 further stated that in this species the dorsal cup is less flattened at the bot- 

 tom, the radials are proportionally larger, and the first costals take part in 

 the lateral walls, and not in the truncated lower portions. Number of arms, 

 position of anus, and form and arrangement of orals and radial dome plates 

 as in the preceding species. 



Horizon and Locality. — Hamilton group ; Alpena, Mich. 



Ti/pes in the Davenport Academy of Natural Sciences. 



Remarks. — We regard this form as a good species, and not a variety of 

 M. nodosus as supposed by Barris ; the difierences are very marked and con- 

 stant. We examined a large nnmber of specimens of both forms, and 

 experienced no difficulty in distinguishing them promptly. 



Megistocrinus rugosus Lyox and Cass. 

 Plate XLVni. Figs. 6a, h, c. 



1859. Lyon and Cass. ; Amer. Joum. Sci., Vol. XSVIH., p. 243. 

 1881. W. and Sp. ; Revision Pateocr., Part II., p. 138. 



Calyx depressed, its height to the base of the anal tube one third less 

 than its width. Dorsal cup shallow basin-shaped, yet considerably higher 

 than the tegmen, three times as wide as high, truncated to the middle of 



