57 



The smallest specimen has only two-thirds the diameter of the one 

 illustrated, and the largest specimen has a diameter one fifth 

 greater than the one illustrated. 



Found in the Hamilton Group, at Charlestown, Indiana, and 

 from the collection of Wm. F. E. Gurley. 



DOLATOCRINUS BELLULUS, n. sp. 



Plate V, Fig. 16, basal view; Fig. 17, azygous, side view; Fig. 



18, summit view. 



Species above medium size. Calyx hemisperical, broadly trun- 

 cated below. Radial ridges consist of small round ridges crossing 

 the central par"t of the plates, and interrupted by prominent nodes 

 in the center of each plate. Nodes larger and more or less trans- 

 verse on the interradials. Surface ornamented by fascicles of 

 lines radiating from the central nodes. Column large, round, and 

 bearing a large cinque-foil columnar canal. 



Basal plates almost covered by the column, and bearing a small 

 circular ridge around the facet for the attachment of the column. 

 First primary radials wider than long, the two on the azygous 

 side being la' ger than the others. Second primary radials about 

 one-half wider than long, quadrangular. Third primary radials 

 expand to the superior lateral angles, longer than the second, 

 pentagonal, axillary, and in two of the rays each bears upon each 

 superior sloping side a single secondary radial, which is axillary, 

 and bears upon each superior sloping side two tertiary radials, 

 which gives to each of these rays four arms. These two rays ad- 

 join the azygous area. In each of the other three rays the third 

 primary radial bears upon one sloping side three secondary 

 radials, and upon the other one secondary radial, which is axillary 

 and supports upon each upper sloping side two tertiary radials. 

 This arrangement gives to each of these rays three arms. There 

 are, therefore, seventeen arms and seventeen ambulacral openings 

 to the vault in this species. 



The azygous area is like the others except a little larger. The 

 first interradials are the largest plates in the calyx, have nine 

 sides and are broadly truncated above for the second interradials. 

 The second interradials are about half as large as the first, and 

 are followed by a single plate in the third range, which unites 

 with plates belonging to the vault. 



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