PALEONTOLOGY OF NEW YORK. 
frontal suture, thus leaving a free median plate upon the epistoma, which is 
elongate-sub-triangular in outline, attenuate at the apex, and recurved at 
the base which forms the anterior portion of the prora. 
Glabella sub-quadrangular, broadest behind; lateral margins slightly 
incurving; angles rounded; length equal to three-fourths the length of the 
cephalon. Surface depressed-convex. Lateral furrows in three pairs, the 
first two of which are short, extending about one-fourth the distance across 
the glabella, and are perpendicular to the margin. The third pair near their 
proximal extremities are bent backward. The third or j)Osterior lobes are the 
strongest, the anterior or frontal lobe having about the same strength as each 
of the first two pairs. Rarely in young individuals, and only under favorable 
preservation, are these furrows and lobes to be seen, since they become 
obsolete at an early stage of growth. 
Cheeks. The movable portions are flattened, and when normally preserved 
are abruptly deflected. They have rarely been observed isolated, although 
the cephalic shield is not infrequently seen with these parts wanting. 
Eyes situated at the summit of strong, elevated nodes, each of which 
occupies nearly one-third the entire surface of the cephalon. These nodes 
are bounded by low sulci separating them from the glabella, occipital ring 
and lateral area. Visual surface small, lunate, covered with minute homo- 
corneal lenses, of which about one thousand have been counted in each eye 
of a small individual. Palpebral lobe capping the visual surface, and sloping 
evenly and abruptly to the palpebral furrow. 
Thorax broad; length equal to the width. Surface depressed-convex, scarcely 
trilobate; lateral portions abruptly deflected; margins approximating pos¬ 
teriorly. 
Axis broad, making two-thirds the width of the body. 
Pleurae narrow, deflected along their median line. 
Each of the segments is broadly rounded or flattened upon the axis, 
the posterior margin infolding over the articulating ring of the next 
succeeding segment. These articulating rings are exposed even where the 
