96 
PALEONTOLOGY OF NEW YORK. 
Pleum flat for one-half their width, thence abruptly deflected to the lateral 
margins. Each segment is grooved by a sharply impressed furrow which 
becomes obsolete at the articulating plane. 
Pygidium semi-elliptical, sometimes a little produced at the posterior extremity. 
Length to width as 4 to 5. Surface elevated, flattened above, deflected at 
the sides. Border broad, widening posteriorly and strongly curved upward. 
Axis convex, tapering evenly to a blunt, somewhat elevated termination 
just within the margin, and bearing thirteen or fourteen annulations, which 
are marked by a faint, impressed longitudinal groove or line just above the 
axial furrows. Each annulation is obliquely flattened and makes a double 
curve in crossing the axis, sloping forward for about one-fourth the distance; 
being angulated at that point, just above the impressed line, and thence 
bending backward in a broad curve to the axial line, along which is a series 
of small nodes giving the axis the appearance of being medially angulated. 
PleurcB flattened or very gently convex for about one-third of their width, 
thence rounding to an almost vertical slope upon the sides. Upon the poste¬ 
rior area the slope is less abrupt. They bear twelve annulations, which are 
separated by moderately broad furrows, and each is distinctly grooved for its 
entire length by a fine impressed line, visible upon the cast as well as on 
the dorsal surface. The anterior annulations encroach for a short distance 
upon the border. 
An HYPOSTOMA found in association with abundant fragments of this species is 
sub-triangular, centrum elongate, regularly convex, anterior margin narrow 
and deflected ; anterior angles broadly sub-auriculate; postero-lateral depres¬ 
sions long but not continuous; posterior sulcus prominent and posterior 
lingua short. 
Surface Ornamentation. The cephalon is covered with fine tubercles and 
granules, which are most abundant upon the glabella, and are also faintly 
visible upon the segments of the thorax and the annulations of the pygi¬ 
dium, The inter-annular grooves of the pygidium appear to be punctate. 
