Description of New Genera of Echinodermata. 25 
on the right bifurcate on the eighth plate, and the second arm to 
the right of the azygous plates bifurcates on the tenth plate; the 
plates are very slightly wedge-shaped, and have their thickest mar- 
gins produced into nodes, the alternate arrangement of which 
gives the arms a rough aspect; pinnules coarse, making the head 
appear full and dense. The first azygous plate rests between the 
first two radials, the under side of the first radial on the right, and 
the second and third azygous plates; the second azygous plate is 
of the same size as the first, rests on the truncated end of a sub- 
radial, and abuts upon a first radial and brachial on the left, the 
first and third azygous plates on the right and another azygous 
plate at the top; the third azygous plate is a little smaller, and 
abuts a brachial on the right. Column and vault unknown. 
Found in the Keokuk Group, at Crawfordsville, Indiana, and 
now in the collection of Wm. F. E. Gurley. 
