ACTINOCRINID&. 619 
but somewhat decreasing in width; moderately flattened on the back, but 
without surface markings; the sides slightly dentate. The spines of the 
pinnules rather short. Interbrachials: 1, 2, 2,1, the first a little larger 
than the costals, The anal plate, which is generally narrower than the 
radials, supports 2, 3, 2, and 1 piece, the latter followed by a narrow elon- 
gate plate, placed between the arm-bearing brachials. Interdistichal spaces 
deeply depressed, and the centre occupied by a small, nodose plate. Ven- 
tral disk very high, the interambulacral spaces slightly grooved toward the 
arm regions. Plates more or less tumid, irregular in form and size. Orals 
indeterminable, and possibly unrepresented. Covering pieces of first and 
second orders represented by single plates; the succeeding orders by two 
rows of small alternate pieces, which take part in the tegmen. Anal tube 
strong, constructed of similar plates to those of the ventral disk, but some- 
what smaller. Column apparently small; axial canal large for the genus 
and quinquelobate. 
Horizon and Locahty. —Same as last. 
Type in the (Worthen) Illinois State collection. 
Cactocrinus cclatus var. spinotentaculus Hatt. 
Plate LIX. Fig. 10. 
1860. <Actinocrinus spinotentaculus —HatL; Suppl. Geol. Rep. Iowa, p. 86; N. Y. State Mus. Nat. Hist., 
Bull. I. (1872), Plate 3.4, Figs. 13 to 17. 
1885. <Actinocrinus spinotentaculus — W. and Sp.; Revision Paleocr., Part III., p. 112. 
Agreeing with C. calatus in the number of arms, the arrangement of the 
plates, and their style of ornamentation ; but departing from it in the form 
and proportions of the calyx, which expands abruptly from the distichals, 
and is at the arm bases almost as wide as high.  Actinocrinus spinotenta- 
culus is in our opinion only an extravagant form of Cactocrinus ccelatus, in 
which some of the arm joints, which in the latter are free, were incorpo- 
rated into the calyx; and this, together with a slight increase in the thick- 
ness of the arms, fully explains the modifications above mentioned. 
Horizon and Locahty.— Same as last. 
Type in the University Museum, Gottingen, Germany. 
