BY R, ETHERIDGE, JUNE., AND JOHN MITCHELL. 491 



usual Cheirurid type, with strong tubercles on the fulcra, sepa- 

 rated from the inner portions by relatively wide and distinct 

 furrows running parallel with the axial grooves, on their outer 

 boundaries these tubercles are bounded by similar but less dis- 

 tinct furrows, distinctly indicating the position of the origin of 

 the spines, which are in length equal to the width of the pleural 

 lobes from which they subtend; they are flat, little or not at all 

 directed backwards, free, gradually tapering to sharp, small, 

 subclaw-like points. 



Pygidium. — Not 3'et found attached; but the following is the 

 description of one associated with the cephalon and thorax above 

 described: -Outline widely triangular, granulate; axis slightly 

 arched, rings three in number and a depressed terminal piece, 

 bounded laterally by a deep sulcus; pleurae of three segments 

 each bearing spines similar to those of the thoracic pleura?, but 

 rather more falcate in outline; centrally is a short, flat, rounded 

 spine. 



Obs. — The cephalon of this species, as pointed out, approaches 

 more closely in general characters to C. quenstedti and C. yibbus 

 than to any others we are acquainted with; but, nevertheless, 

 the species is widely different from either of them. The cephalon 

 of our trilobite and that of C. insignis are even generically 

 different, but, between the thoraces and pygidia of these species, 

 there is much in common with each other. For instance, the 

 spines of the pleural lobes of both thorax and pygidium are much 

 alike, the width of the thorax including the spines in both is 

 equal to the width of the cephalon between the genal angles, 

 and the spines are very similar; but the differences in the glabella 

 of these two separate them completely, and many less important 

 differences could, were it necessary, be pointed out. It is re- 

 markable that this Bowning fossil, as is also the case with other 

 trilobites from the same area, should possess striking features of 

 structure common to two or more Bohemian species of Cheiruridae. 



Loc. and Hor. — Bowning Creek, Parish Bowning, County 

 Harden; Limestone Creek, Parish Derringullen, County King 

 (J.M.;: Hume beds. Parish Yass, County Murray (Jenkins): 

 Bowning Series (Yass-Hume beds;. Upper Silurian. 



