BY R. ETHERIDGE, JUNR., AND JOHN MITCHELL. 
501 
Phacops mansfieldensis, sp.nov. 
(PL xxxix., fig. 12.) 
Sp. char. — Head-shield or cephalon. — Twice as wide as long. 
Glabella subpentagonal, rounded in front, very tumid, intensely con- 
tracted behind by the intercalary furrow, sides straight and nearly 
perpendicular; intercalary furrow distinct and terminating on each 
side in remarkably deep punctures, intercalary ring prominent and 
nodular at base; no lateral glabella furrows noticeable; neck furrow 
distinct, and as it passes into the axial grooves forms very deep 
punctures or pits, continuing across the lateral lobes with equal 
distinctness; neck ring highly arched, curving back and nodular; 
fixed cheeks small, genal lobe prominent, highly arched; palpebral 
furrow distinct, passing posteriorly round and under the eye; 
axial grooves wide and deep. Eyes prominent, large, rather 
longer than half the length of the cheek, separated from the 
thickened edges of the cheeks by wide or shallow furrows ; free 
cheeks coalesced, margins thickened and straight in front of* the 
eye, giving to the cephalon a triangular character; genal angles 
terminate in short spines. 
Obs. — We have only a decorticated cephalon of this species, 
which has unfortunately been somewhat contorted and is appa- 
rently an immature individual; but the features present clearly 
separate it from other known Australian forms. Foremost among 
these features are the genal spines, the great contraction of the 
glabella by the intercalary furrow, and the very deep punctures 
on each side of this furrow and of the neck furrow. The genal 
spines separate it from all described Australian species of this 
genus. It is further separated from our other Victorian species 
by having the nodules of the intercalary ring behind the glabella 
basal lobes instead of in the axial grooves. The great contraction 
of the glabella by the intercalary arch gives to the tumid portion 
of the glabella a subcircular contour. The greatest number of 
eyelets in a vertical row appears to be six. 
