592 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
little beyond the sides of the column; column facet concave. Radials once 
and a half as wide as long, the sides rapidly spreading. First costals fully as 
wide as the radials, but considerably shorter, subquadrangular in outline, but 
generally hexangular. Second costals a little longer than the first, and 
directed slightly downward, as also the distichals. Distichals nearly as large 
as the second costals, and all axillary, supporting upon each side two moder- 
ately large palmars, which are laterally connected and support the free arms, 
of which there are four to the ray. Arms simple, long, heavy, rounded in 
the lower portions, flattened and wider in the upper; the tips incurving. 
The two proximal arm plates cuneate, the two rows of ossicles succeeding 
them moderately long, and every sixth one extended into a sharp lateral 
spine. The spines increase in length upwards, commencing as small nodes, 
and attaining at the upper part of the arms a length of 2 or 8 mm., the cor- 
responding ones placed opposite. First interbrachial comparatively small, 
higher than wide, followed by two rather large plates in the second row, and 
one or two smaller interambulacral pieces at each side. Anal plate remark- 
ably small, only half as wide as the radials, supporting two plates, which are 
followed by three large and two smaller ones at the sides, the latter bending 
outward, helping to form the free rays. Plates of the ventral disk slightly 
convex, their surface covered with small pustules without definite arrange- 
ment. Orals a little larger than the other plates, and formed into short 
spines ; the posterior one placed at the side of the anal tube. Anal tube 
excentric and very short, directed obliquely upward. No ambulacral plates 
are visible to the base of the free rays, where those of the first and second 
order are represented by single plates. Column composed of rather long 
jomts; the nodal ones considerably widest and rounded along the margin; 
the axial canal small and pentagonal. 
Horizon and Locality. — Lower Burlington limestone; Burlington, Iowa, 
and Lake Valley, New Mexico. 
Itemarks. — This species is readily distinguished from all others by its 
arm structure. | 
Type in the (Worthen) Illinois State collection at Springfield. 
Y 
