BY R. ETHERIDGE, JUNR., AND JOHN MITCHELL. 
505 
continuous, conspicuously deflected laterally; genal angles pro- 
duced into strong spines reaching to the sixth segment of the 
thorax; neck furrow distinct, particularly where it joins the axial 
furrows, continuing across the lateral lobes subfalcately with 
increasing distinctness and width; facial sutures anteriorly rather 
straight to the border, thence continuous, posterior portions from 
the hinder ends of the eyes passing out laterally and falcately, 
cutting the borders of the free cheeks in a line with the base of 
the eye. Eyes large, each has 32 to 40 or even more vertical 
rows of lenses with a normal number of eleven in each central 
row, and in odd cases twelve to fourteen, giving an aggregate of 
about 400 lenses in a single eye of some mature specimens; the 
lentiferous face forms a subsemicardioid curve, above sloping back- 
ward at an angle of about 40°, below bounded by a shallow groove, 
height diminishing more gradually posteriorly than anteriorly; 
lenses spherical, closely packed in the vertical rows, which are 
separated by distinct spaces or partitions. 
Thorax.— About equal in length to the combined width 
of one pleural lobe, and the axis or about two- thirds of 
its total width, and greater than that of either the head or tail, 
suboblong or subfusiform; axis subfusiform, greatest width 
at fourth or fifth segment, where it is slightly greater 
than the width of the neck ring; arched most prominently 
posteriorly, rather flat anteriorly; segments thickened at their 
bases, moderately arched; some axes show faint trilobation 
caused by feeble depressions traversing their length, these depres- 
sions are accentuated by rows of tubercles, one on each side, about 
midway between the central line and the axial groove; pleurae 
one and one-third times as wide as the thorax, and between the 
axial grooves and fulcra rather horizontal, outer ends moderately 
deflected and recurved, the latter feature becoming more pro- 
nounced posteriorly; pleural grooves wide and shallow, beginning 
at the angles of junction with the axial grooves and passing out 
posteriorly at the bases of the claw-like ends, thus traversing the 
pleurae diagonally, anterior ridges much stronger than the pos- 
terior, and passing across to the posterior edges at about midway 
