INVERTEBRATES. 309 



second row of anal plates another -series is only partly visible. Inter- 

 radials, one or more to each space, but their form and number can 

 not be clearly determined from the specimen in hand. 



Column round, larger at its junction with the body than below, 

 and composed at first of thin, even joints, but below thicker plates 

 are intercalcated at irregular intervals. 



Position and locality : Kinderhook group of the Lower Carbon- 

 iferous series, Marshalltown, Iowa. 



Dedicated to Mr. Thos. Fletcher, of Keokuk, Iowa, to whom I am 

 indebted for this and other interesting fossils. 



The author's collection. 



GENUS CYATHOCRINUS, Miller. 

 CYATHOCBINUS PAEVIBEACHIATUS, Hall. 



Pt. XXVIII. Fig. 5. 



Cyaihocrinus parvibrachialuf, HALL, 1861. Desc. New Crinoidoa. 



Cyathocrinus Hamiltonensis, WOBTHEN, February, 1882. 



Bulletin No. 1, of the Illinois State Museum of Natural History, p. 32. 



Body of medium size, basin-shaped, base deeply impressed, width 

 of body about twice as great as the height to the top of the first 

 radial series. Basals small and concealed in the basal concavity by 

 the upper joints of the column. 



Subradials hexagonal, counting three angles on the under side, 

 and curve into the basal concavity ; width and length nearly equal ; 

 slightly convex, the greatest convexity being a little below the center 

 of the plate. 



Radials about twice as wide as long, those on the anterior side 

 pentagonal, the articulating facet for the reception of the brachials 

 occupying about one-half the width of the plate. In the anterior 

 ray the first bifurcation takes place on the fourth brachial, and in 

 one of the antero-lateral rays on the third, and a second bifurcation 

 on each division of this ray takes place on the third plate above the 

 first. The arms diminish rapidly in size beyond the first bifurca- 

 tion. Anal side unknown. 



