The anal pieces consist of one large octagonal, and a great 
many small polygonal plates. The first, which is the largest piece 
in the boJy, is higher than wide, rests directly on the base, and 
extends above the summits of the radial plates. The lateral bor- 
ders are nearly parallel, and the superior edges bear five small 
plates, ne mae rere ranges of nine or ten plates, —- 
m and s = of these pieces are smooth, 
a or meer ‘slightlf-< conve 
vault is composed ork a ‘great many polygonal pieces, which 
are vb variable in size: some of them are flat, or slightly con- 
vex, some are very convex, and others are Sickel into promi- 
nent spines. The principal oe is wedge-shaped, and ae 
on one side directly above the anal opening from which it 
y three o 
‘lyx, and much flattened on the anal side. It is divided ito six 
longitndinal lobes, five of which stand directly over the radial pie~ 
ces, and the sixth over the large anal piece. The former are 
quite neem and are separated from each other by deep, lon- 
gitudinal furrows; but the anal lobe is slightly prominent, and the 
furrows on either side very shallow. 
The cis is lateral, and situated on the anal side; but, ce 
fortunately, the specimen is fractured at this part, sot that its 
tion is merely indicated by an aperture, surrounded by many hints 
— plates. 
Arms.—The number of arms, as above stated, is twenty, but 
only one or two of the first joints are preserved i imen. 
times the width of the first arm joints, excepting that on the anal 
side, which has a width equal to about six of these joints. = 
Column.—A single plate of the column still adhe: 
ed, and this not perfect. It i 
