ORDOVICIAN FAUNAS. 207 
lower than the first, directed obliquely forward; third pair of glabellar 
furrows directed toward the axis of the glabella for a short distance 
and then bending abruptly backward and joining the occipital fur- 
row, leaving the small, basal glabellar lobes wholly detached. Occi- 
pital furrow rather deep and broad. Occipital segment rather broad, 
its elevation about even with the glabella in front, its posterior mar- 
gin convex. Palpebral lobes prominent, their elevation being nearly 
that of the glabella, separated from the glabella by the deep dorsal 
furrow, and marked by a conspicuous furrow just within the border 
of the eye. Hyes large, lunate, their inner margins elevated nearly 
or quite to the height of the glabella, their anterior ends opposite the 
first glabellar furrows and their posterior ends reaching nearly to 
the occipital furrow. Cheeks, outside the eyes, sloping rather abruptly 
to the lateral margins of the head; marked along the posterior margin 
to a point about one-half the distance from the eye to the margin by 
the narrow, but rather sharply impressed, occipital furrow, whose 
distal extremity is rather abrupt; the lateral borders marked by an 
ill-defined marginal furrow, which originates at the outer extremity 
of occipital furrow, and, after passing forward nearly parallel with 
the margin, joins the dorsal furrow just in front of the eye. 
Pygidium subtriangular in outline, rather abruptly rounded or sub- 
angular posteriorly. Axis prominent, but rather narrow, its margin 
shghtly incurved and abruptly rounded behind, marked by from 
eight to ten somewhat sinuous annulations; the plure slightly flat- 
tened adjacent to the axis, but soon curving rather abruptly to the 
lateral margins, marked by about six grooved segments, with slight 
traces of others posteriorly. 
Surface of the glabella, palpebral lobes, occipital segment and 
cheeks inside the marginal furrow distinctly pustulose, the little 
tubercles being more or less irregular in size; upon the cheeks out- 
side the border of the eyes the pupille are much less conspicuous 
than upon the glabella and the marginal border is perfectly smooth. 
Pygidium unornamented, except by the grooves marking the seg- 
ments, which do not extend entirely to the border, thus leaving a plain, 
perfectly smooth, narrow marginal border. 
