318 THE SILURIAN TRILOBITES OF NEW SOUTH WALES, 



ingly small, the thoracic segments five in number, and the pygidium 

 almost as large as the thorax and cephalic shield combined (PI. xxv. 

 fig. 2d). In the next stage the glabella is more fully developed, 

 but the segments of the thorax remain the same in number. 



Log. and Horizon. — Bowning Creeek, Bowning, Co. Harden 

 (Coll. Mitchell) ; Lower Trilobite Bed of the Bowning Series — 

 Upper Silurian (? Wenlock). 



Proetus australis, sp.nov. (PI. xxv., figs. 3, Za-e). 



Sp. Char. — Body oval or elliptical. Cephalic shield semi-ellip- 

 tical ; axial length greater than that of the thorax, and much 

 greater than that of the pygidium. Glabella rather short, squarish 

 or subrectangular, moderately prominent, equal in length to the 

 pygidium ; basal pair of lateral furrows distinct, and nearly 

 circumscribing the basal lobes ; neck furrow moderately distinct ; 

 neck segment wide, gently arched ; axial furrows moderately 

 distinct and continuous in front of the glabella; facial sutures 

 anteriorly straight to the thickened edge of limb, thence incurving 

 along it, behind cutting the posterior margins of the shield at 

 about one-third their distance from the axial grooves ; fixed 

 cheeks small : eyes moderately large and reniform ; free cheeks 

 large and somewhat tumid ; genal angles produced into very long 

 and gently incurved spines, which completely embrace the thorax ; 

 limb wide, with a thickened edge, and striated on the under 

 surface, the shield between it and the anterior edge of the glabella 

 being much flattened. Thorax of eight segments, width twice 

 that of the length ; axis moderately arched, tergal portion rather 

 flat, almost twice as wide anteriorly as posteriorly ; axial furrows 

 distinct ; pleurae gently directed or curved backwards, terminating 

 distally in short claw-shaped spines. Pygidium semi-elliptical, 

 twice as wide as long j axis short, half the length of the pygidium, 

 more or less in the form of a truncated cone j pleurae flat, five or 

 six in number, faintly furrowed ; limb striated ; surface present- 

 ing a faint appearance of granulation. • 



Obs. — Proetus australis is an interesting species, as by the 

 nearly circumscribed basal lobes it shows a tendency to take on 



