ACTINOCRINID 2. 631 
the second still smaller, being considerably shorter. The size of the distich- 
als is but little less than that of the upper costals, but the plates of the suc- 
ceeding orders are considerably smaller. There are five bifurcations in each 
main division of the ray, and six arms, or twelve to the ray. Arms moder- 
ately long, much larger than those of the preceding species, laterally com- 
pressed at their lower ends, and distinctly angular on the back throughout. 
The arm joints are transversely angular, and have a small elevation or 
sharp node at each end, giving to the section of the arm a trigonal outline. 
Pinnules provided with long hooks, similar to those of Cactocrinus. Inteyr- 
brachials: 1, 2, 2,2; the latter on a level with the distichals, and quite 
small; the first as large as the first costals, or larger. Anal plate as large 
as the radials, followed by 2, 8, and about 6 irregularly arranged plates above, 
which are roofed by the palmars. Interdistichals one. Tegmen moderately 
convex, slightly plicated near the outer margins, and composed of large 
plates scattered among smaller ones. The sutures between the plates dis- 
tinctly grooved, but the surface flat, and covered with wrinkles, which give 
it a decidedly granular appearance. Anal tube central, long, rather large 
around the base, but decreasing rapidly to two thirds its largest size, and 
then tapering slightly to the end. The tube consists of short, very wide 
pieces, arranged in transverse rows, and covered with wrinkles like those of 
the tegmen. It is surrounded at half way to the margin of the disk by an 
irregular ring of ten to fifteen large, spinous plates, which sometimes 
bifurcate, and rise to a height of from 40 to 80 mm. It is barely possible 
that these plates represent the orals and radial dome plates, or the latter 
only, but if so their arrangement is very irregular. Column beautifully 
sculptured with six rows of large angular processes, longitudinally arranged, 
which give to the stem a distinctly hexangular outline. 
Horizon and Locality.— Lower part of Upper Burlington limestone, 
Burlington, Iowa. 
Type in the (Worthen) Illinois State collection, Springfield. 
femarks. — This species is most nearly related to Teleiocrinus wmbrosus 
Hall, but differs in never having more than twelve arms, even in the largest 
specimens; besides the arms are much stronger, and angular on the back 
instead of flattened. It also differs in the shape of the rim, and the aspect of 
the ventral disk, its wrinkled surface, as well as the long spines; and it is 
very distinct in the sculpturing of the column. 
Comparison with the types shows that Actinocrinus clivosus, A. erodus, 
and A. insculptus, all described by Hall, are Synonymous with this species. 
