The genus Brachymetopus was founded by McCoy in 1847, and the generic characters were drawn from the Australian species Br. Strzeleckii, McCoy, which was at the same time described. The specific characters of this form were very briefly given, the leading features having been mentioned in the diagnosis of the genus. Dr. Henry Woodward in 1884 gave a new summary of the generic characters differing somewhat from that originally furnished by McCoy, being modified in such a way as to include the European or British species, Br. ouralicus, De Vern., Br. Maccoyi, Portl., Br. discors, McCoy, and Br. hibernicus, Woodw. The original type-specimens of Br. Strzeleckii used by McCoy (op. cit.) in drawing up the description of the genus, and figured by him at the same time, are in the Woodwardian Museum, to which they were presented in the year 1844 by the Rev. W. B. Clarke. They come from the Carboniferous Shale of Dunvegan, New South Wales. The specimens comprise three complete head-shields, two of which are hollow impressions and one a cast, and portions of three or four others; there are also three casts of complete pygidia, one perfect impression, and fragments of two others. This material demands a fuller description of the specific characters than McCoy furnished, particularly as this type-form of Brachymetopus shows features differing in several respects from those of the better known European species ascribed to the same genus. McCoy's description (op. cit.) of the species was as follows:—

“Glabella widest at the base, with one very minute, obscurely marked, cephalothoracic furrow at the base on each side; all the segments of the pygidium with an irregularly tuberculated ridge along the middle; lateral segments forming large tubercles where they join the thickened limb, opposite each of which is a short slender spine projecting from the margin”.