CRUSTACEA. 
117 
Facial Sutures normal. 
Glabella sub-conate, sides broadly tapering to the anterior extremity, where 
it is closely appressed upon the narrow, reflexed margin. Width three- 
fourths the length. Surface convex, anterior slope normally abrupt or 
vertical, curving posteriorly and becoming horizontal at the occipital furrow. 
Under normal preservation only a single pair of lateral furrows is visible. 
These are the fourth or basal furrows and are very strong and deep, taking 
their origin nearly opposite the anterior angle of the eye and extending to the 
occipital furrow, thus forming two strong conspicuous lobes. Upon casts of 
the lower surface, and in extremely rare instances upon the dorsal surface, 
there is evidence of the first, second and third pairs of furrows, with 
faint indications of the accessory furrows. Occipital lobes prominent; 
occipital furrow narrow, broadly bifurcating about the occipital lobes, and 
becoming deeply impressed and broadened upon the cheeks; occipital ring 
broad and posteriorly convex, narrowing upon the cheeks. 
Eyes not large, lunate; palpebral lobe inconspicuous; palpebral sulcus nar¬ 
row and deep. 
Cheeks deeply grooved about the orbit of the eye, and abruptly depressed 
to the broad marginal sulcus. 
Thorax sub-rectangular; surface convex and equally trilobate; length to 
width as 1 to 1.8; composed of ten segments which are arched upon the 
axis and considerably elevated above the pleurae, obliquely flattened and 
transverse. 
The pleurae are flattened for less than one-half their width and abruptly 
deflected to the margin; segments sulcate, anterior and posterior limbs nearly 
equal, the former becoming abruptly obsolete at the fulcrum. 
Pygidium large, semi-elliptical, convex; length to width as 2 to 3. 
Axis having less than one-third the width of the shield upon the anterior 
margin, and tapering to a blunt termination within the border. Annulations 
thirteen or fourteen, with an anterior bend near the margins, and a broad 
curve over the median line; in most individuals, the annulations are slightly 
