196 PALEOZOIC PALEONTOLOGY. 
to indicate an internal thickening of the test; the two anterior pairs 
are short and lie in front of the eye-lobes; they are close together, 
and are directed obliquely backward from the margin of the glabella; 
the posterior pair are more conspicuous than the others, and are 
sometimes marked by shght depressions; they are situated a little 
in front of the middle of the eye-lobes, and are directed obliquely 
backward from the margin of the glabella, becoming more curved 
posteriorly, joining the occipital furrow at nearly right angles. The 
dorsal furrow well defined throughout. Oecipital furrow sharply im- 
pressed, deeper than the dorsal furrow. Occipital segment with sub- 
parallel margins, scarcely as highly elevated as the glabella, marked 
by a small, rounded tubercle at its central point. Palpebral lobes 
of moderate width, subsemi-circular in outline, depressed below the 
level of the glabella. Facial sutures curving into the margin of the 
glabella, both in front and behind the palpebral lobes; posteriorly 
they intersect the margin of the head close to the axial lobe; in front 
of the palpebral lobes they curve outward nearly to the margin of 
the head, where they make a rather sharp bend and recurve inwardly, 
intersecting the anterior margin at some distance from its median 
point. Anterior limb of the cranidium broad, with a convex marginal 
border, between which and the glabella there is a rather broad, shal- 
low, concave furrow. Free cheeks depressed-convex, with the eyes 
abruptly elevated, marked by a rather broad marginal border on 
both the lateral and posterior margins, on the inner side of which 
there is a rather sharply impressed furrow. Pygidium small, sub- 
semi-circular in outline; the posterior margin regularly rounded; 
the anterior margin straight nearly to the lateral angles, where it is 
curved backward. Axis narrow, not reaching to the posterior mar- 
gin, marked by six or seven annulations. Plure convex, much de- 
pressed below the axis, marked by five or six grooved segments, only 
the anterior two or three of which reach the margin of the pygidium. 
Thorax unknown. 
The entire surface of well-preserved specimens is finely granulose. 
Remarks.—This species resembles P. parviusculus Hall. No meas- 
urements of that species are given with the description, but the figured 
type specimen, when reduced to natural size, has a total length of 
head of only 2.6 mm. None of the New Jersey specimens are as 
small as this, and the larger ones have a length of head of 8 mm. 
The lateral furrows of the glabella are also said to be not visible in 
that species, but at least the posterior pair can always be detected 
