PALAEONTOLOGY OF NEW-YORK. 
Genus Spilerocystites (n.g.). 
[ Gr. tfpaipa, splicer a; xvtfng, vesica .] 
Body spheroidal, wider than high. Arms in two principal pairs, with 
numerous bifurcations. Brachial sulci obliquely lobed. Mouth longitudi¬ 
nal ? apicial : anus subapicial : ovarian opening upon the summit. Basal 
plates four; those of the series above not determined. Base depressed. 
Column unknown. 
Tliis fossil, though having the general aspect of Callocystites , or Lepadocrinus , I 
have characterized as a distinct genus, from the remarkably rotund form, the nu¬ 
merous branching arms, the position of the ovarian opening upon the summit, and 
the narrow elongated pectinated rhombs, the two upper of which are remarkable for 
being upon the summit and having their direction almost precisely at right angles 
to each other. The whole fossil is silicified; and from this cause, and the numerous 
ramifications of the arms, the junction of the plates is obliterated; but the depressed 
spherical form, and the disposition of the rhombs, indicate an essential modification 
of the plates compared with Lepadocrinus. 
Plate YII A. Fig. 1-4. 
Body spheroidal : height or length a little less than the transverse dia¬ 
meter ; length from anteal to posteal extremity greater than the trans¬ 
verse diameter. Base excavated for the reception of the column. Basal 
plates four : plates of second and higher series unknown. Ovarian 
aperture at the summit, midway between apex and margin. Mouth 
central and longitudinal? Anal pore subapicial, a little upon the left 
side. Pectinated rhombs extremely narrow and elongated, scarcely dis¬ 
similar in form : as many as forty bars may be counted in a single one 
of these spaces. 
Arms in two pairs, composed of small plates lodged in shallow lobed 
grooves, which are numerously and irregularly divided below till the 
entire surface is covered by their ramifications. 
Column unknown, but probably similar to that of Lepadocrinus. 
