42 



four of them apparently pentagonal but really hexagonal, 

 because of abutting two baeal plates, one of them heptagonal, 

 by reason of being truncated by the second azygous plate. 

 The lower ends curve abruptly into the columnar cavity and 

 the superior ends more gently upward toward the acute angles 

 between the first radials. First radials one-third wider than 

 high, truncated the entire width above, thickened within and 

 separated from the second radials, on the outer face, b^^ a 

 gaping suture, but immediately within, a straight ridge extends 

 from one outer angle to the other, having a furrow on each 

 side, so as to form a hinge, on which the second plate articu- 

 lates. Second radials of three kinds; the one opposite the 

 azyous area is twice as long as wide, rounded externally, con- 

 tracted in the middle, serrated or bearing small nodes at the 

 lower end, where it projects beyond the first radial, and axil- 

 lary at the superior end, where it bears two arms. The plates 

 on each side of the azygous area are of the same form but 

 shorter and project farther beyond the first radials, where the 

 nodes ai"e stronger, and the central one almost spine-like. The 

 two lateral second radials are still shorter, having a width and 

 depth, each, greater than the length, and projecting still more 

 beyond the first radials, showing a remarkably wide gaping 

 suture. The central nodes are really small spines. Each second 

 radial bears upon the upper sloping sides two arms which 

 make ten arms in this species. 



The arms are composed of a single series of rather long 

 plates, each one of which L-ears a central tubercle or node. 



The first azygous plate is quadrangular and rests between 

 a subradial and the under sloping side of the first radial on 

 the right. It does not appear to abut upon a subradial below, 

 but comes to a point near the angle. The second azygous 

 plate truncates a subradial and rests between the superior lat- 

 eral side of the first radial on the left and the upper sloping 

 side of the first azygous plate on the right. The third azygous 

 plate truncates the first and abuts against the very short 

 lateral side of the first radial on the right. The second radials 

 and the arms are quite different from anything heretofore de- 

 scribed and will serve to distinguish it from all other species. 

 Possibly,- it may belong to Zeacrinus, though it has no close 



