10 Belt — On the Fauna of the '^Lingula Flags.'" 



Conocoryphe? bucephala, spec. nov. (PL 11. Fig. 1-6). Length If in. 

 Breadth 1 in. Ovate. 



Head broadly semi-circular with strong spines pointing downwards and a little out- 

 wards. Glabella subconical. truncated, very prominent, and without furrows when 

 perfect. Figs. 1 and 2 ; but when crushed Fig. 3, or divested of outer crust Figs. 4 

 and 5, showing two pairs of internal ones of which the upper is short and the lower 

 long and very oblique, reaching nearly to the neck furrow. Some specimens show a 

 third short pair of furrows near the apex of the glabella. Eyes small and 

 prominent, distant from the glabella about half its width and joined to it by 

 ocular ridges that are nearly obsolete in perfect specimens of the head, but clearly 

 shown in crushed ones. Frontal limb narrow, with a strong triangular margin 

 marked off by a deep groove. Cheeks broad, prominently convex, with a wide margin. 



Thorax of 14 (?) rings. Axis convex, tapering. Pleurae falcate, pointed strongly, 

 grooved, and facetted. Fulcrum of the pleurae prominent, less than half their length 

 distant from the axis. (See PL II. Fig. 6.) 



Fyc/idium not preserved in any of the specimens, but it must have been small and 

 of not more than one or two rings. 



The specimens of this species when perfect have all their parts prominent and convex. 

 The head is large and resembles C. ? depressa, Sal., and that species also when un- 

 crushed shows no glabella furrows, in which condition it is C. 2 verisimilis, Sal., and 

 probably also C. ? vexata, of the same author. Specimens of C, ? bucephala, flattened 

 by pressure, resemble Olenus micrurus, Salter, to which species I was at one time 

 inclined to refer it, but an examination of the specimens of O. micrurus, from near 

 Trawsfynydd, in the Museum of Practical Geology, has convinced me that it is a true 

 Olenus and quite distinct from C, ? bucephala. C. ? hucephala is not uncommon at 

 Gwern-y-barcud, near Penmaen-pool ; on Mynydd Gader, and near Craig-y-Dinas, 

 along with Hymenocaris vermicauda, Bellerophon Camhriensis, and a small Lingula in 

 Upper Festiniog beds, 



SpJi^ropJithalmus hisulcatus, Phil. ; syn., Olenus hisulcatus, Phil. Olenus 

 (SpceropJithalmus) pecten, Salter. Olenus {Sphceropth.) jiagelUfer, Sal. 

 Olenus alatus, Sal. 



I have examined the specimens in the Museum of Practical Geology, on which the 

 above species were founded. They are fragments only, variously distorted. When 

 they are studied in connection with the perfect specimens that we have now obtained 

 from the Dolgelly district there can, I think, be no doubt of their being one and the 

 same species. I think the species cannot be referred to Olenus fSphar.) alatus, Boeck, 

 unless we assume a large amount of error in Angelin's figure of that species, as he 

 shows the pygidium entire and with four axial rings, whereas Sph. hisulcatus has a 

 minute serrated pygidium of two rings only, and is furnished with a long terminal 

 spine. Some fragments of Sphcei^oph. alatus, Boeck, in the Museum of the Geological 

 Society resemble Sphceroph. humilis, Phil., but that species also has a minute pygidium 

 with a long terminal spine. At the same time I think it highly probable, that when 

 we are able to compare our Cambrian trilobites with specimens of the Scandinavian 

 species, many of our names will have to give place to those of Angelin, though we 

 cannot at present identify them by the figures he has given us, 



Mr, E. Williamson discovered this species in the black shales at Rhiw-felyn in 

 1865, More recently, Mr. J- C, Barlow found it in great profusion within a few 

 yards of the first discovery. A band of about three inches thick of the shale, is 

 almost entirely composed of the remains of S. hisulcatus, along with a few specimens 

 of S. humilis. 



Agnostus ohtusus, spec. nov. (PI. II. Figs. 15, 16). Length Jin., 

 breadth Jin. Oblong, obtuse. 



Head, a truncated semi-circle. Glabella five-eighths length of head, ovate, 

 obtuse, with a nearly obsolete central tubercle, and traces of a nearly obsolete 

 furrow, separating a terminal lobe. Two minute triangular lobes at base of glabella. 

 Limb nearly of equal width all round. Margin narrow. 



Thorax, of two rings. Axis, broad. 



Fyyidium, shaped like head. Axis, short, pentangular, one-third the length of the 

 pygidium, with a nearly obsolete tubercle, near the end. Limb narrow at the sides, 

 and broad at the end of the axis. Margin marked ofi" by a deep groove, and 

 widened near the lower angles, where it has a short spine on each side. 



This species belongs to the same group as A. tardus. Bar,, A. lentiformis, Ang., and 

 A. trinodus, Sal., from all of which it differs in the much shorter and unlobed axis of 

 the pygidium. In the Upper Dolgelly beds at Rhiw-felyn, I have found this species 



