29 



ZEACRINUS PIKENSIS. N. SP. 



Body of medium size, sliort, forming below the summit of the 

 radial series a shallow cup, about three times as wide as high. 

 Basals small and entirely concealed in the basal concavity. Subra- 

 dials rather longer than wide, and curving below so as to form a 

 part of the concavity of the base. 



Kadials pentagonal, once and a half, and the anterior one proba- 

 bly twice as wide as long, and truncated squarely across their upper 

 margins for the reception of the brachial series. 



The anterior ray has three brachials, the first one of which is as 

 large as the radial below, the second one very short and both quad- 

 rangular ; the third is also short but pentangular, supporting on 

 its sloping sides the first divisions of the ray. One of these divisions 

 bifurcates again on the eighth plate, and the other on the tenth, 

 beyond which they appear to be simple to their extremities, making 

 but four arms to this ray. The right antero-lateral ray and the left 

 posterior ray have each a single brachial, which is nearly as long 

 as wide, supporting on its sloping angles the first divisions of the 

 rays. The two divisions of the right antero-lateral ray divide again 

 on the sixth plate, and at least one of these divisions, and probably 

 both the outer ones divide again on the tenth plate, making six arms 

 to this ray. If the other rays correspond with this, it would give 

 twenty-eight arms as the full series for this species. Anal plates 

 unknown. Column slender, and composed of round joints of unequal 

 thickness. 



Position and locality : Lower part of the Burlington limestone, 

 Montezuma, Pike County, 111. 



Illinois State collection. 



RHODOCEINUS COXANUS. N. SP. 



Body of medium size, subglobose, base slightly depressed, the 

 basal plates concealed by the first columnar joints. Subradials 

 a little wider than long, their lower angles curved in to form a part 

 of the basal concavity. 



The first radials much larger than the succeeding ones, heptag- 

 onal in form. Second radials nearly quadrangular, and the third 

 hexagonal, supporting above the secondary radial plates, of which 

 there is but one to each division of the ray. 



Brachials four to five, short, widening above, the upper one with 

 a slightly projecting angle in the middle, separating the first divi- 

 sions of the arms. From two to five single wedge-formed pieces suc- 

 ceed the brachials, above which the arms are composed of a double 

 series of short, interlocking pieces, each one of which gives ofl" a 

 moderately strong pinnule. In one of the specimens under exami- 

 nation, the arms on the two rays visible, continue single after the 

 first bifurcation, making four arms to each ray, but in another 



