60 
PALEONTOLOGY OF NEW YORK. 
broader and deeper on the cheeks, occipital ring prominent and bearing short 
and sharp central spine; narrowing to the axial furrows, thence rapidly 
widening to the genal spines. 
Eyes lunate, large and elevated considerably above the summit of the 
glabella, and closely appressed against its coalescent first and second lobes. 
Visual surface with numerous corneal lenses, the single specimen (a young 
individual) in which they may be enumerated, showing eighteen rows, 
counting diagonally from the lower posterior margin, and one hundred and 
ninety-two lenses. Palpebrum scarcely prominent; palpebral lobe depressed 
and sloping abruptly to the narrow and elevated palpebral furrow. 
Cheeks sloping abruptly from the ocular node to the thickened and some¬ 
what flattened margin. A deep sinus, which is stronger in old individuals, 
bounds the ocular node and flattens the subjacent portion of the cheek. 
Thorax sub-rectangular, length to width as 4 to 5. Surface depressed-convex. 
Axis relatively narrow, widest at about the fifth segment, tlience regularly 
tapering to the pygidium. 
PleurcB relatively broad, flat for about one-half their width and thence 
rounded to the lateral margins. 
Each segment has a slight forward curve along the axial line, being sulcate 
on the pleurm and having the anterior limb abbreviated by the beveled 
planes of articulation. 
Pygidium sub-triangular, depressed-convex or flattened. Posterior extremity 
produced into a stout, upwardly curved spine, usually short, but sometimes 
equaling the pygidium in length. Length, including the caudal spine, equal 
to the width. 
Axis having less than one-third the width of the shield on the anterior 
extremity, regularly tapering to an obtuse, broadly rounded termination, and 
composed of from nine to fourteen broad, flat, transverse annulations. 
Pleum broad and rounding more or less abruptly to the margins, bearing 
eight or nine wide, flattened annulations, which become obsolete just within 
the border. Wherever the crust is retained the annulations are seen to be 
