536 Dr. H. Woodward—On the Pores in Trilobites. 
BRACHYMETOPUS DISscoRs, M‘Coy, sp. 1844. 
Phillipsia (?) discors, M‘Coy. 1844. Synop. Carb. Foss. Irel. p. 161, t. 4, fig. 7- 
Brachymetopus discors, M‘Coy. 1847. Ann. and Mag. Nat. Hist. vol. xx. p. 230. 
Morris. 1854. Cat. Brit. Foss. p. 101. 
Salter and H. Woodw. 1865. Cat. and Chart. Foss. Crust. 
p- 16, fig. 120. : 
H. Woodw. 1877. Cat. Brit. Foss. Crust. p. 27. 
This species is founded on a pygidium only, and was in the first 
instance (1844) referred by M‘Coy to Phillipsia, with a query. 
He afterwards, in 1847, placed it under his genus Brachymetopus. 
“Sp. Ch. Pygidium semielliptical; axal lobe reaching to the 
margin, one-third less in width than the lateral lobes, very con- 
vex, composed of 17 narrow segments, the third and fourth united 
in the middle of the lobe to form one large tubercle, and towards 
the apex there are four or five small tubercles, irregularly disposed ; 
the lateral lobes have only six large rounded segments each, termi- 
nating at the margin in a large rounded tubercle, and having usually 
between the margin and the axal lobe, two other large obtuse tuber- 
cles, one of these on the last being probably spiniferous; beside 
these there are a few irregular granules, especially towards the apex, 
all the lateral segments seem forked from nearly their origin.” ? 
We have no further information to give concerning B. discors, and 
the only additional specimen we have seen is from the Carboniferous 
Limestone of Little Island, Cork; it consists of a very small decor- 
ticated pygidium, and was obtained by Joseph Wright, Esq., of 
Belfast. The specimen is very obscure and not well preserved. 
Bracuymerorus Hrpernicus, H. Woodw., sp. nov. Pl. XIII. Fig. 3. 
Cephalothorax unknown. Pygidium broadly semicircular, 13 
millimétres wide and 8 mm. long; axis narrow, 84 mm. broad and 
63 mm. long, composed of eleven coalesced segments, each alternate 
ring ornamented bya small tubercle on the centre ; border composed 
of ten rounded pleurz which extend to the margin, becoming gra- 
dually more and more oblique until. the last pair become nearly 
parallel behind, uniting the extremity of the axis with the posterior 
border. There is no ornament on the pleure. This pygidium 
slightly resembles &. discors in general form, but is quite distinct 
and well marked. I feel satisfied that it belongs to Brachymetopus, 
but it cannot be referred to any species hitherto described, nor have 
I seen but one specimen, which, however, is very perfect. 
Formation.— Carboniferous Limestone. 
Locality.—Kildare, Ireland. 
Obtained by the present Earl of Enniskillen (when Lord Cole), 
and now preserved in the British Museum (Natural History). 
—_——_— 
Nore on THE Nature oF CERTAIN Pores OBSERVABLE IN THE 
CEPHALON oR H¥#AD-SHIELD OF soME TRILOBITES. 
MONG the numerous specimens of Carboniferous Trilobites 
which I have had the opportunity to examine during the last 
three years, many examples exhibit a peculiarity of structure which 
had already arrested the notice of such keen observers as Portlock, 
1 M‘Coy, Ann. & Mag. Nat. Hist. 1847, vol. xx. p. 230. 
