52 TRILOBITES OF GIRVAN. 



Pygidium semicircular, with flattened border marked off by marginal furrow. 

 Axis conical, gently tapering to rounded extremity, about one fourth the width and 

 three fourths the length of the pygidium ; consists of three well-marked segments, 

 of which the posterior is the largest (in the Grirvan specimen a faint transverse 

 furrow divides the posterior segment into two). Axial furrows strong, deep. 

 Lateral lobes bear a few (2 — 3) feeble radiating furrows, of which only the first is 

 distinct. 



Remarks.— This species has been described and figured by Nicholson and 

 Etheridge (op. cit.) from Whitehouse Bay, but only the glabella was known to 

 them. A pygidium has since then been found, and some further details regarding 

 the head-shield may be added. In one of our specimens a portion of the eye and 

 free cheek is preserved ; the eye consists of very numerous closely placed hexagonal 

 lenses arranged in diagonal rows. A deep furrow separates the eye from the very 

 narrow rounded band-like free cheek, which decreases to a mere rim anteriorly and 

 is ornamented with transverse arched coarse lines. The epistome is preserved in 

 another specimen and is seen to lie immediately below and behind the eyes ; it has 

 a transverse crescentic shape with its anterior margin strongly arched forward and 

 its posterior margin concave to a less extent ; and its surface is marked from side 

 to side by a few coarse striae. 



The typical Bohemian forms seem to have the glabella of a more regular oval 

 shape and slightly contracted at the base. In the Grirvan specimens the glabella 

 is decidedly broadest at the base and narrows anteriorly ; but this appears to be 

 the only difference, and is perhaps more or less due to the state of preservation. 

 No well-preserved thorax has been found. 



( 'ollections. — Mrs. Gray ; Museum of Practical Geology ; Edinburgh Museum. 



Horizon and Locality. — Whitehouse Group (M. Bala) : Whitehouse Bay. 



2. Cyclopyge rediviva (Barrande), 1840. Plate VIII, figs. 2, 3. 



1846. Mjle rediviva, Barrande, Notice Prelim., p. 34. 



1847. Cyclopyge megacephala, Corda, Prodr. Mon. Bohm. Trilob., p. 64, pi. iv, fig. 32. 

 1852. JEglina rediviva, Barrande, Syst. Silur. Bohcme, vol. i, p. 665, pi. xxxiv, figs. 3 — 13. 



1880. Cyclopyge rediviva, Nicholson and Etheridge, Mon. Silur. Foss. Girvan, fasc. iii, p. 284, 



pi. xix, fig. 4. 

 1899. Cyclopyge rediviva, Mem. Geol. Surv., Silur. Eocks Brit., vol. i, Scotland, pp. 517, 672, 688. 



Specific Characters. — Body subrectangular, rounded at both extremities; triloba- 

 tion faint, except on thorax. 



Head-shield elongate oval, truncate posteriorly, nearly half the entire length of 

 the body, convex, not trilobed, nor subdivided into glabella and cheeks. A pair 



