= s A ——— - : : 
eee —_= = : ee ——————— 
ACTINOCRINID &. 605 
Cactocrinus reticulatus (Hatz). 
Plate LVIIT. Figs. 2a, b. 
1861. Actinocrinus reticulatus— Hawi; Descr. New Spec. of Crin. (prelim. notice), p. 2, and Boston 
Journ. Nat. Hist., p. 269. 
1881. <Actinocrinis reticulatus —W. and Sp.; Revision Paleoer., Part II., p. 145. 
Syn. 4. thous Hat; 1861, Descr. New Sp. Crin. (prelim. notice), p. 11. 
Syn. A. locellus Hatt; 1861, ibid., p. 15. 
Nearly as large as the preceding species. Calyx sub-ovate; the dorsal 
cup a little higher than the ventral disk, obconical, spreading uniformly to 
the top of the distichals, thence abruptly to the arm bases; the plates con- 
vex, and ornamented as in C. prodoscidalis. Basal cup trilobate, short, thick- 
ened at the lower margin, and projecting downward over the top of the 
column ; interbasal sutures deeply grooved. Radials and costals decreasing 
in size upwards, the radials nearly twice as large as the second costals. Dis- 
tichals and palmars in single rows, the latter projecting outward. Arms four 
to the ray, except in the two posterior ones, in which the palmars next to 
the anal side support two post-palmars, giving to these rays five arms, or 
twenty-two to the species. Arm facets large, subovate. Arms long, heavy, 
and but very slightly tapering; they are cylindrical in the lower portions, but 
flatten toward the tips, and are composed of two series of moderately long 
pieces, united by parallel sutures, and bordered by four longitudinal rows of 
sharp nodes, two of them occupying the sides, the two others the back. 
Regular interbrachials: 1, 2, 2,1; the last, which rests between the pal- 
mars, sometimes unrepresented. Anal plate followed by 2, 3, 2 and 1 plate, 
the upper one separating the post-palmars. Ventral disk sub-conical, cov- 
ered with well defined spines, irregularly arranged, some of them bi- and 
tri-partite, separated by smaller convex pieces. Anal tube central or nearly 
so, of moderate size, its length unknown. Column of medium size, composed 
near the calyx of alternate thick and thin joints, the former with undulating 
edges ; axial canal rather large and pentangular. 
Horizon and Locality. — Lower Burlington limestone ; Burlington, Iowa. 
Type in the University Museum at Ann Arbor. 
Remarks. —This species is readily recognized by its arm formula, its 
heavy and spine-bearing arms, and by the spinous plates of the ventral disk. 
Under the name Actincerinus locellus, Hall redescribed this species without 
the tegmen, and under A. ¢hoas a specimen with the arms attached. 
