PROETUS. 55 



26. Brachymetopus hibernicus, E. Woodiv., 1883. PI. VIII, fig. 16. 



Beachtmetopub hibebnictts, H. Woodw. G-eol. Mag., Decade ii, vol. x, p. 536, 



pi. xiii, fig. 3, 1883. 



Cephalothorax unknown. Pygidium broadly semicircular, 13 mm. wide and 

 8 mm. long ; axis narrow, 3^ mm. broad and 6| mm. long, composed of 11 

 coalesced segments, each alternate ring ornamented by a small tubercle on the 

 centre; border composed of 10 rounded pleurae, which extend to the margin, 

 becoming gradually 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 pleurae. 



This detached pygidium slightly resembles B. 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 any 

 other but the one figured, which is a very perfect and well-preserved specimen. 



Formation. — Carboniferous Limestone. 



Locality. — Kildare, Ireland. 



Obtained by the present Earl of Bnniskillen (when Lord Cole), and now 

 preserved in the British Museum (Natural History). 



Genus 4. — Proetus, Steininger, 1830. 



When the earlier pages of this Monograph were passing through the press, I 

 was not aware of the existence of any evidence in favour of the introduction of 

 the genus Proetus into the catalogue of our British Carboniferous-Limestone 

 Trilobites. 



So long ago, however, as 1861, Prof. Dr. James Hall had identified a Trilobite 

 from the Waverley Sandstone of New York State as Proetus auriculatus (* 15th 

 Eeport on State Cabinet of New York,' 1862, p. 107). 



Dr. R. Richter, in his paper " Der Kulm in Thuringen " (in the 'Zeitschrift 

 der Deutschen geolog. Gesell.,' 1864, Bd. xvi, p. 160, Taf. iii, fig. 1), describes 

 and figures a small Trilobite under the name of Proetus posthumus, but there 

 does not appear any special reason, save the narrowing of the glabella in front, for 

 separating it from the genus Philllpsia. 



In 1865, Messrs. Meek and Worthen also described a Trilobite from the Lower 

 Carboniferous series (Kinderhook Group), Jersey, Co. Illinois, which they named 

 Proetus ellipticus (' Geol. Survey of Illinois,' vol. iii, " Palas ontology," p. 460, pi. 

 xiv, fig. 8). 



8 



