Eight New Species oj Tlolocystites from the jSFicKjara Group. 133 



the coliuim upward about one third the length of the bodj'. Summit 

 rounded; central part covered with a large hcptagonal plate; five plates 

 abutting this central one are pentagonal and gradually slope off in all 

 directions; the other two form part of the margin of the ambulacral 

 orifice. The ambulacral orifice is situated on the left side of the sum- 

 rait, at the margin; it is sub-elliptical in outline and surrounded by 

 five free arms. The thickening of the plates around this orifice gives 

 the fossil the appearance of a slight prolongation to the left. The 

 mouth is situated upon the anterior side two plates distant from the 

 central one, at the apex, and separated by two plates from the ambu- 

 lacral orifice. It is sub-(!lliptical and surrounded b}' five plates. The 

 body is covered with fifteen or more irregularly disposed ranges of 

 plates. The plates vary greatly-, in size and shape. A range of large 

 plates, eight in number, surrounds the body above the middle; part or 

 all of these have nine sides ; the next range below seems to be com- 

 posed of twenty pentagonal plates, but the anterior side of the speci- 

 men examined is injured so as to prevent us from certainly ascertain- 

 ing the number. The plates in other ranges vary in number, size and 

 shape, so that we may sa}' the plates, in the fifteen ranges, vary from 

 seven in one range to twenty in another, and in form, from a triangle 

 to a nonagon. The illustration shows their appearance on the posteri- 

 or side. 



The surface is strongly granulose and each plate is perforated with 

 numerous pores. The pores open on the summit of the granules. No 

 anal aperture. Column unknown. 



The specimen illustrated has a length of four inches, and it would 

 require one or more ranges of plates to complete it down to the column. 

 The circumference, immediately below the mouth, where the plates are 

 all preserved, is three and eight tenths inches; the diameter from the 

 anterior to the posterior side nearl}^ an inch, and the transverse diam- 

 eter one and three tenths inches. 



Collected by Prof. A. G. Wetherby, Frederick Braun, and the author, 

 in the lower part of the Niagara Group, in Ripley County, Indiana. 



Hoi.oCYSTiTES GLOBOsus, u. sp. (Plate v., figs 5, 5a, 56.) 



Bod}' sub-globose. Basal pieces, apparently seven, but I am by no 

 means certain that this is correct. Between the basals and the first 

 range, on the posterior side, three small plates appear to be inserted, 

 two of which are pentagonal, and the other triangular. The body is 

 covered, between these pieces and the arms, with four ranges of eight 

 plates each. In the first range, part of the plates are pentagonal, the 

 others hexagonal; in the other three ranges the plates ai'e hexagonal. 

 The ambulacral orifice is situated at the apex, and is surrounded by 



