PALEONTOLOGY OF NEW YORK. 



margin, to the eye, thence forward at nearly right angles, to the frontal mar- 

 gin, where they pass over upon the doublure, gradually approximating, and 

 terminating on the epistomal margin. These lateral branches are united 

 by the transverse frontal suture just below the frontal margin, thus leaving 

 a free median frontal plate. 



Glabella large, trapezoidal or sub-quadrate in outline; widest posteriorly, 

 where the width nearly equals the length of the cephalon ; convex, tumid 

 on the frontal lobe; dorsal and anterior furrows strong and deeply impressed; 

 lateral furrows in three pairs, the first of which is faint and almost obso- 

 lete, the second short and broad, the third longer, curved slightly forward, 

 bifurcating near its anterior extremity, the posterior branch having a retral 

 bend. Frontal lobe sub-hemispherical, gibbous ; second and fourth pair of 

 lateral lobes transversely pyriform, the latter much the stronger and having 

 a diameter equal to one-fourth the posterior width of the glabella; third pair 

 inconspicuous, and seen only under favorable preservation. 



Occipital furrow narrow on the axis, widening on the cheeks; occipital 

 annulation broad, elevated, becoming flattened on the cheeks toward the genal 

 angles. 



Cheeks broadly sub-triangular, depressed convex ; free portions triangular, 

 small. 



Eyes small, situated somewhat anteriorly; palpebral lobe depressed, broad, 

 making the visual surface distant from the glabella; palpebral furrow deep 

 and strong. 



Thorax sub-equally trilobate, margins sloping posteriorly. Length and width 

 equal. 



Axis broadest at about the fifth segment, thence tapering evenly to the 

 pygidium. 



Pleura deflected along the fulcrum at about one-third their width from the 

 axial furrows. 



The thirteen segments have a slight double curve upon the axis, bending 

 backward at a short distance from the axial margins, thence forward again 



