464 CARBONIFRItOUS THILOBITES OF AUSTRALIA, 



appear to have been spinate. The length of the cephalic shield 

 was approximately 30 mm. 



Thorax: greatest width approximately 45mm., length 27mm., 

 finely granulated. Axis moderately convex, and had a spread 

 of 15 mm., and hence equal to one side-lobe. These lobes were 

 fairly convex, greatest width 15 mm., and the mesial furrows of 

 each pair of the segments were wide and shallow along the 

 articulating faces (ridges), the sutures are plainly visible in 

 decorticated specimens. 



Pygidiuyn: greatest width 41 mm., length 34 mm.; serai-elliptic, 

 moderately convex; axis mildly convex, tapering very gradually 

 posteriorly, ending bluntly at the inner edge of the border, much 

 narrower than one side-lobe, practically two-thirds as wide as 

 one side-lobe, the width being 11 : 15, rings apparently eighteen, 

 strong, densely and finely granulated, valleys narrow : axial 

 furrows narrow and distinct; pleurae moderately convex; ribs, 

 fifteen pairs, reaching to the thickened outer margin of the 

 border, and having a decided backward curve in the portions 

 traversing the border; mesial valleys fairly deep, ridges strong, 

 and bearing two or more rows of closely placed granules, and 

 articulating sutures plainly visible^ each succeeding pair gradu- 

 ally inclining posteriorly, border wide but ill-defined, not con- 

 tinuous and concave, margin thickened and upturned. 



Q})s — The first fragment of this gigantic Carboniferous trilo- 

 bite was briefly described by Mr. Etheridge, Junr.,* and for it 

 he suggested the specific name gratidis. Subsequently,! he de- 

 scribed a pygidium from New South Wales, which he placed 

 specifically with the Queensland pygidial fragment. Very 

 reluctantly, I have to disagree with this latter determination of 

 Mr. Etheridge, and am compelled to give the New South Wales 

 fossil separate specific rank. A recent discovery of a nearly 

 perfect tail, portions of a cephalic shield, and thorax, in the Mt. 

 Morgan area, Queensland, has much simplitied the task of 

 separating the two forms. This recently discovered specimen 



* Geol. and Pal. Queensland and New Guinea, 1892, pp. 215-216, 

 t Mem. Geol. Survey N. S. Whales, Pal. No.5, Pt. ii., 1892, p. 128, text- 

 fig. o, and PI. xxi., fig. 5. 



