116 PALEOZOIC PALEONTOLOGY. 
at Franklin Furnace than any other trilobite. If in the future more 
perfect specimens of this trilobite should be secured, and its identifi- 
cation as Olenellus should be confirmed, this association of the two 
genera, Olenellus and Dikelocephalus, in the same fauna would be a 
remarkable occurrence. 
PTYCHOPARIA BLAIRI N. Sp. 
Plate I., Figs. 10-13. 
Description.—Glabella small, tumid, longer than wide, the sides 
subparallel, the front regularly rounded and reaching to the anterior 
margin of the head. It is marked by two pairs of well-defined, lateral 
furrows, which divide it into three nearly equal parts; the anterior 
pair of furrows are straight and each one extends about one-third the 
distance across the glabella; the second pair are straight at first and 
then bend backward somewhat abruptly, towards the occipital furrow ; 
in length they about equal the anterior pair. The occipital furrow 
is well defined and is continuous across the glabella; the occipital 
segment is rather broad, with the posterior margin parallel with 
the occipital furrow. The fixed cheeks are only imperfectly known, 
but are apparently strongly depressed below the glabella, are rather 
broad behind, becoming narrower anteriorily, and are not continuous 
around the anterior extremity of the glabella. Free checks unknown. 
Pygidium minute, strongly convex, semi-circular in outline; the axis 
highly elevated above the plure, occupying more than one-third the 
total width, and tapering to the rather sharply-rounded posterior 
extremity, which reaches to the posterior margin of the pygidium ; 
divided into five segments by four transverse furrows, which become 
less and less strongly marked posteriorly; the plure convex, with a 
narrow marginal border, divided into four segments. 
The dimensions of an average-sized head are: length, 2.8 mm.; 
approximate width, 6.5 mm. 
Remarks.—This species occurs near Blairstown, and is known only 
from imperfect specimens of the head and pygidium. The glabella 
is frequently well preserved and is abundant, but in no case have the 
cheeks been observed in a perfect condition. 
