BRACHYMETOPUS. 53 



seems no reason to doubt their relation to each other. The side-ribs of the 

 pygidium of B. Maccoyi differ from those of B % ouralicus in being simple, whereas 

 in the latter they are grooved, and each appears like a double rib. 



This species has only been met with in Ireland. Our figures are drawn from 

 specimens in the collections of Joseph Wright, Esq., F.G.S., of Belfast, and the 

 Geological Survey of Ireland, Dublin. 



Subjoined we give Portlock's original description ofPhillipsia (Brachymetopus) 

 Maccoyi, Portlock, sp., 1843. — " Of this minute but very beautiful species the 

 cephalothorax alone has as yet been discovered. It is placed provisionally in 

 this genus (Phillipsia), though, from its diminutive size some of the characters 

 of the genus cannot with certainty be exhibited, such for example, as the 

 furrows of the glabella or the reticulation of the eyes. Cephalothorax elevated ; 

 general form oval, approaching to semicircular; length "17", breadth *25" ; 

 glabella very small, in length rather more than two thirds of the length, and 

 in breadth one fourth of the total breadth of the cephalothorax; the eyes 

 apparently smooth, lunate, and equal in length to two thirds of the height of the 

 glabella ; the cheeks are large, slightly convex, separated from the margin by a 

 furrow which joins the neck furrow, and is continuous, passing in front round the 

 glabella. Margin or wings (free-cheeks) elevated, and ending at the posterior 

 angles in prolonged points ; the whole surface is covered with granulations, which 

 are arranged along the ridge of the margin and the supra-palpebral line of the 

 eyes like beads." (' Geol. Londonderry,' p. 309.) 



Prof. M'Coy, in his ' Synopsis of Carboniferous Fossils of Ireland,' p. 162, 

 refers to this species as follows : 



" The only specimen which has occurred of this species I collected myself from 

 the Carboniferous Limestone of Kildare ; it was lent to Captain Portlock for his 

 1 Monograph of Irish Trilobites,' as I conceive it to be not only a new species, but 

 the type of a new genus. I am still inclined to think it cannot be ranked with 

 any known genus ; the very small size of the glabella, and large size of the eyes, 

 distinguish it from the most nearly allied, and from Phillipsia, with which 

 Captain Portlock has ranked it ; it is distinguished by the want of the cephalo- 

 thoracic furrows. As I have, however, no means of examining the specimen now, 

 I cannot characterise it. Length of cephalothorax two lines, width three lines." 



