432 PALEONTOLOGY OF ILLINOIS. 



This is another species related to Zeacrinus spinobracliiatus, of Dr. 

 White, but it (lifters in having decidedly more slender arms below the 

 bifurcations, with the arm pieces, particularly above the first bifurcation, 

 arranged much more in zigzag, and their thicker ends more projecting 

 on each side. It is one of the forms combining some of the characters 

 of Zeacrinus and Scaphiocrinus. 



Locality and position Upper division of the Burlington group, Bur- 

 lington, Iowa. Lower Carboniferous. No. 323 of Mr. WACHSMUTH'S 

 collection. 



ZEACRINUS LYRA, M. and W. 



PL 1, Fig. 11. 

 Zeaerinus lyra, MEEK and WORTHEN. Proceed. Aoad. Nat. Sci., Phila., 1869, p. 152. 



BODY short, obconical, or expanding very rapidly from 

 the column to the top of the first radial pieces, where it 

 is about twice as wide as high. Base not concave but some- 

 what projecting, and about one-third as high as wide; trun- 

 cated near three-fourths its breadth by the slightly concave 

 facet for the attachment of the column. Basal pieces pre- 

 senting a small pentagonal facet above the column, two or 

 three times as wide as long, with lateral margins so short 

 as to appear nearly triangular. Subradial pieces of moder- 

 ate size, about as wide as long, three hexagonal and two on 

 the anal side heptagonal. First radial pieces generally 

 about twice as large as the subradials, near once and a half 

 as wide as long, and all pentagonal, with the upper side 

 equaling the entire breadth. Second radial pieces of very 

 nearly the same size and form as the first, though the fifth 

 angle and sloping sides are of course above instead of 

 below; each supporting two arms all around. Anal plates 

 nearly all hexagonal, and, as usual, arranged in a double 

 alternating series, the first resting between the superior 

 sloping sides of two of the subradials, under one side of 

 the first radial on the right, and connecting above the mid- 

 dle on the left, with another resting on the superior trun- 

 cated side of one of the heptagonal subradials, and joining 



