84 



The first azygous plate is hexagonal, as wide as long, very 

 tumid or bulged out in the central part, rests between the 

 upper sloping sides of two basals, separates two first radials 

 and is followed by two plates that are not preserved in our 

 specimen. The two superior faces are concave. The vault is 

 unknown. 



This species is extraordinary because there are only four 

 arms; because the first azygous plate rests between the upper 

 sloping sides of two basals, and because the plates are pitted. 

 The specimen is well preserved and in its normal condition. 

 The hole shown in the illustrations does not appear to pass 

 through the test and may not properly belong to the species 

 as a character of any importance. 



Found in the Niagara Group, at St. Paul, Indiana, and now 

 in the collection of Wm. F. E. Gurley. 



ORDER CYSTOIDEA. 



Family HOLOCYSTID^. 



HOLOCYSTITES ASPER, n. sp. 



Flate V, Fig. 1, summit view; Fig. 2, anterior side view. 

 Body medium size, subovate most tumid on the left anterior 

 side, plates large, convex, covered with large pastules and 

 pierced with numerous pores; sutures deeply impressed. The 

 specimen illustrated has the lower part broken away, so whether 

 or not it was sessile cannot be determined, and probably two 

 ranges of plates are gone; five ranges of plates only are pre- 

 served. 



The first range of plates preserved, which is, in fact, the 

 second or third range, consists of four large plates and four 

 smaller ones, the latter are on the anterior side and may be 

 seen at the bottom of figure 2, The second range has eleven 

 plates, of unequal size; the third range has eleven plates, the 

 fourth range six, and the fifth range, that surrounds the ambu- 

 lacral orfice, at the center of the summit, has six plates. There 

 are no intercalated plates between the ranges in our specimen. 



The mouth is surrounded by five plates and is submarginal 

 between the range that surrounds the ambulacral orifice and 

 the next range below. Four of the plates that scrround the 

 ambulacral orfice have spine bases. 



