BATOCRINID. 389 
costals, and thence abruptly to the arm bases, which stand out horizontally, 
forming a projecting rim. The radial plates are somewhat elevated or 
rounded, while the other plates of the dorsal cup are flat and without orna- 
mentation. Suture lines indistinct. 
Basal cup short, cylindrical, wider than the column, and very little con- 
cave at the bottom. Radials twice as large as both costals together, their 
upper faces concave. Costals of about equal size, transversely arranged ; 
the first quadrangular; the second pentangular. Distichals 210, resem- 
bling the costals in form and size. Palmars 2X20 in the calyx; subquad- 
rangular, and in contact laterally. Arm facets lunate, directed outward, 
the respiratory pores small, and placed at the sides of the ambulacral 
openings. Arms four to the ray, exceptionally two in the anterior one; 
they are very long, broadly paddle-shaped, and biserial from the second 
free plate. To nearly two inches from the calyx, they are rather thin and 
cylindrical, whence they grow perfectly flat, and increase rapidly to the 
width of eight to nine mm., which is slightly reduced toward the extremities. 
The flat portions are thickest along the median line, the sides being knife- 
like with serrated edges, which turn slightly outward. At two-thirds their 
height, the arms generally curve inward until their tips touch the calyx. 
The proximal arm plates are quite short, but the plates increase to twice 
their former length as they widen. Pinnules long, composed of long, flat 
joints. Interradials, 1, 2,1; the first very large, reaching the top of the 
distichals. The anal plate is followed by three and two plates. Ventral 
disk conical, somewhat bulging, often higher than the dorsal cup. The 
plates are highly convex or conical, and of nearly uniform size. Anal tube 
slightly excentric, rather short and slender. Column small. 
florizon and Locality. — Upper Burlington limestone, Burlington, Iowa. 
Types in the University Museum at Ann Arbor, Mich. 
Remarks. — Professor Hall’s description of this species is so indefinite 
that little can be made out of it, and if it were not for his figures, which he 
distributed privately among some of his colaborers eleven years later, the 
species could not be distinguished from several others which occur in the 
same locality. He gives the number of arms as sixteen; stating, however, 
that there were imperfections in his specimen. Either Hall described one 
species and figured another, or the number of arms given is erroneous, 
