52 CARBONIFEROUS TRILOBITES. 



those English specimens which agree in having a pygidium like that figured by 

 de Verneuil associated with a head-shield like those on our PL VIII, figs. 1, 2, 3, 

 4, and 5. Should, however, fuller information be obtained rendering it necessary 

 to separate the Russian species, these must of course retain the original name of 

 ouralicus, and for this English form I would then propose that the name ornatus 

 should be adopted. 



24. BitAcnYMETorus Maocoyt, Portloch, sp., 1843. PI. VIII, figs. 9 — 13. 



Phillipsia Maccoti, Portlock. Geol. Rep. Londond., p. 309, t. 11, fig. 6, 1843. 

 Bbactiymetopus Maccoti, M'Coy. Ann. and Mag. Nat. Hist., vol. xx, p. 230, 



1847. 



— Morris. Cat. Brit. Foss., p. 101, 1854. 



— H. Woodw. Gat. Brit. Foss. Crust., p. 27, 1877. 



— — H. Woodw. Geol. Mag., Decade ii, vol. x, p. 535, 



pi. xiii, fig. 2, 1883. 



Carapace not quite twice as broad as it is long, rather pointed in front; 

 surface sparsely covered with small tubercles ; base of the glabella equalling one 

 third the breadth of carapace, and one half the length of shield (without the neck- 

 lobe) ; basal lobes small, distinct ; no facial suture visible ; eyes large, placed on 

 the highest point of cheeks, and wider apart than the base of the glabella ; rim of 

 the head- shield ornamented by a single row of tubercles, margin strongly grooved 

 or channelled, outer rim slightly raised ; posterior border of cheeks marked by a 

 distinct margin equal in width to the neck-lobe, and separated by a groove corre- 

 sponding to the neck-furrow ; latero-posterior angles produced into spines ; 

 thoracic somites not known (probably nine in number). Axis of pygidium com- 

 posed of fifteen coalesced somites, tapering to an obtuse extremity ; each somite 

 having about five small tubercles on the axis, and about as many on the eight 

 simple lateral lobes ; ribs ending abruptly near the margin of pygidium. 



Formation. — Carboniferous Limestone. 



Localities. — Ballysteen and Monaster, Ireland. 



B. Maccoyi approaches very closely to the preceding species (B. ouralicus), but 

 differs in its smaller size, in the more marked and raised rim of the anterior border 

 to the head-shield, in the less highly ornamented surface of the carapace, in 

 which the eyes are larger in proportion and placed wider apart, and the angles of 

 the cheeks are produced into spines which probably reached to the sixth free 

 segment of the thorax. The thorax is unknown. The pygidium is detached, but 

 occurs in the same matrix and from the same locality as the head- shield, and there 



