BY R. ETHERIDGE, JUNE., AND JOHN MITCHELL. 501 



Phacops mansfieldensis, sjy.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. 



Ohs. — We have only a decorticated cephalon of this sj^ecies, 

 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 deej? 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 

 l)y 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 aj^pears to be six. 



