ACTINOCRINID &. 603 
Cactocrinus lucina (Hatz). 
Plate LVI, Kgs. 8,9. 
1861. <Actinocrinus lucina — Hat; Prelim. Descr. New Paleoz. Crin., p. 11. 
1881. Actinocrinus lucina—W. and Sr.; Revision Paleocr., Part IL., p. 144. 
Syn. Actinocrinus puteatus Rowiny and Hare; Kansas City Scient., July 1891, p. 101, Plate 2, 
Fig. 16. 
A small species. Calyx biturbimate; the sides to the top of the costals 
very slightly convex, the distichals somewhat spreading. Plates a very little 
elevated, and covered with obscure radiating ridges. 
Basals quite small, barely projecting over the sides of the column; the 
suture lines distinctly grooved. Radials and anal plate very little larger 
than the costals; the latter twice as large as the distichals, which support 
two arms, making four to the ray, with frequently an additional arm in each 
of the posterior rays. Arms delicate, three to four times as long as the 
height of the dorsal cup, uniserial to the fourth or fifth plate, flattening in 
their upper portions, and somewhat wider at midway than at either ex- 
tremity. The distichals apparently consist of two pieces forming a syzygy, 
and another syzygy occurs between the first and second palmar, the lines of 
union at both places being much more obscure than between the other 
plates. The third, fourth, and occasionally the fifth palmar are long and 
cuneate, all above arranged in double rows. The free arm plates are 
thickened at their upper edges, and the sides distinctly serrated. Inter- 
brachials at the regular sides five to six, at the anal side nine to ten. 
Ventral disk nearly as high as the dorsal cup, the plates very uniformly 
subspinous. 
Horizon and Locality. — Lower Burlington limestone ; Burlington, Iowa, 
and Louisiana, Mo. 
Remarks. — Hall described this species with five arms in the two posterior 
rays. What is supposed to be the type specimen in the Museum of Com- 
parative Zodlogy, and two others, show four arms in all five rays; but in 
others the posterior rays have five. The form is intermediate between 
C. proboscidalis and C. reticulatus, differimg from them in the smaller size of 
the arms; very probably it is a young stage of the latter, and should be 
made a synonym. 
