BY R. ETHERIDGE, JUNR., AND JOHN MITCHELL. 717 



Thorax. — Apparently consists of nine segments, length equal to 

 the width, sparsely granulated; axis prominent and as wide as 

 the side lobes, nodules inconspicuous; axial, furrows moderately 

 distinct; lateral lobes horizontal, pleural ridges moderately con- 

 spicuous, the anterior pleural margins raised into ridges, and 

 giving to the pleurse the appearance of being centrally furrowed 

 instead of being ridged; pleural spines on the first, second and 

 third pairs of pleurpe moderately reflected and much smaller than 

 those situated more posteriorly; the latter are very long, hastate, 

 robust and intensely fleeted backwards, centrally fluted when 

 compressed; secondary or anterior spines small, paddle-shaped, 

 subfalcate, having entire margins, and the appearance of articu- 

 lation to the pleurae. 



Pygidium. — Triangular, two and a half to three times as wide as 

 long, granulated distinctly; axis veiy prominent, one-half to two- 

 thirds of the length of the pygidium, unsegmented, bearing one 

 prominent ring ; axial furrows faint ; side lobes flat, undivided, 

 one pair of pleural i-idges present, extending from the ends of the 

 axial ring, borders inconspicuous; pleural spines sti'ong, acicular, 

 converging, and about as long as half the pygidial width, but 

 except for these the border is practically entire, although under a 

 lens very minute spination or serration is visible along the whole 

 margin. 



Obs. — Mr. Ratte figured {loc. cit.) two imperfect glabella? of 

 this species and referred them to A. mira, Barr., but as will be 

 readily seen by a comparison of the descriptions and figures of 

 the two fossils they ax-e widely dissimilar. This species was after- 

 wards characterised, fully described and figured by one of us. 



C. longispina is so clearly distinct from all the other Australian 

 species of the genus that it is unnecessary to point out the 

 divergencies. Its chief characteristics are : the practically spine- 

 less cheek borders; presence of three pairs of lateral glabella lobes; 

 the very large occipital spines which are borne by a cowl-like 

 appendage originating at the back of the central glabella lobe, 

 instead of originating in the occipital ring; the massive principal 



