136 Cincinnati Societij of Natural History. 



range of plates below the arm bases is 5^ inches ; the diameter from 

 the anterior to the posterior side, 1 85-lOOths inches; transverse diame- 

 ter, or diameter from the left to the right side one and one half inches. 

 Collected by Frederick Braun, Esq., in the lower part of the Niagara 

 Group, in Jefferson County, Indiana. 



HoLoCYSTiTES ELEGANS, n. sp. (Plate VI., figs. 3 and 3«,) 



{TS.iy.—Elegam, elegant.] 



Body quite irregular in shape; from the column toward the summit, 

 it is somewhat obconoidal, with one side much more rapidly expanding 

 than the other; approaching the summit it becomes sub-quadrate- 

 The summit is moderately convex. The body is covered by numerous 

 olates, which, if regularly disposed, would constitute not less than ten 

 ranges. They are so closely anchylosed, in our specimen, that they 

 can not be accurately counted. Some of the ranges, and particularly 

 those surrounding the sub-quadrate part of the body, must contain at 

 least twenty plates, and probably more. ISone of the plates are very 

 large. 



The ambulacral orifice is very large, and situated a little anterior to 

 the central part of the summit. It is surrounded by eight plates, five 

 of which suppoi't arm bases. 



The mouth is situated near the anterior edge of the summit, a little 

 to the left of a line drawn through the middle of the bod}'. No anal 

 aperture discovered. 



The surface is granulose and all the plates are poriferous. In addi- 

 tion to the minute pores which penetrate all the plates, there are a 

 number of large circular openings irregularly dispersed over the sum- 

 mit, sides and posterior part, down to the column. Some of these 

 openings are found at the junction of two or more plates, in other cases 

 an opening passes through the central part of a single plate. None of 

 of them seem to be pectinated, and we are at a loss to determine what 

 function should be ascribed to them, or what name they should bear. 



The round apertures, upon tlie summit of //. Wetherbiji, seem to 

 be of the same character, but as tliey are not so numerous and are con- 

 fined to the immediate locality of the larger apertures, their functions 

 may have been different. 



Length of specimen one and one half inches; circumference five and 

 one tenth inches; diameter from the anterior to the posterior side oae 

 and six tenths inches; transverse diameter one and one half inches. 



(Collected by Frederick Braun, Esq., in the lower part of the Niagara 

 Group, in Jefferson County, Indiana. 



