BY JOHN MITCHELL. 483 



convex, nearly twice as long as they are broad, with no visible 

 suture separating them from one another in front of the glabella: 

 margin broad and slightly grooved, angles of cheeks produced 

 posteriorly into spines. The entire surface of the head covered 

 irregularly with a small bead-like ornamentation." 



"Thoracic segments unknown, probably nine."' 



" Pygidium consisting of a vai iable number of segments, from 

 ten to seventeen, according to species, the axis tapering rapidly 

 to a bluntly rounded extremity, each segment of axis ornamented 

 with bead-like granulations, ribs with a double furrow extending 

 nearly to the border which is smooth and rounded."' 



This description also includes quite a number of features that 

 possess only specific significance. 



(General A. W. Vogdes* summarises the characters of the 

 genus thus: — 1. Glabella short, tumid. 2. No short lateral 

 furrows on the glabella. 3. Basal lobes distinct. 4. Eyes small, 

 placed close to the glabella. 5. Axis of the pygidium has ten to 

 seventeen segments. 



To this may be added —6. Facial sutures absent. 7. Axial 

 furrows continue round the glabella-front. 8. Ornamentation 

 bead like. 



R. F. Cowper Reedf has suggested a genus or subgenus 

 {Brachymetopina) for the European forms without defined 

 cephalic margins, and non-spinate pygidial margins. 



Brachymetopus STRZELKCKii McCoy, 1847. 

 Brachymetopus strzeleckii McCoy, 1847, ojk cit., p. 231, PI, xii., 

 fig.l. De Koninck, Foss. Pal. Nouv. Gallesdu Sud, 1877, p.352, 

 PI. xxiv., figs. 10, 10a, b,c. Vogdes, Trans. Acad. Sc. St. Louis, 

 Vol. V. (1892), p.617. Etheridge, R., Junr., Mem. Geol. Surv. 

 N. S. Wales, 1892, Pal. No.5, Pt. ii., p.l24. Reed, Geol. Mag., 

 N.S., Dec. iv.. Vol. X., 1903, pp.193-196. 

 (Plate liii., figs.3-6). 

 McCoy's brief description is as follows : — "»S'p. Cha?-. Glabella 



* "North American Carboniferous Trilobites." Ann. New York Acad. 

 Sci., vi., 1888, p.70. 



tGeol. Mag., N.S., Dee, iv., Vol. x., p.i96, 



