82 TRILOBITES OF GIRVAN. 



ring, encroaching slightly on glabella. Occipital fnrrow strong, bending forwards 

 slightly in middle and at sides in front of occipital lobes. Axial furrows narrow, 

 distinct. Fixed cheeks very narrow at base, but widening out in front of eye-lobes 

 and confluent in front of glabella by pre-glabellar area. Eye-lobes large, long, 

 extending more than one third the length of glabella from base, very approximate 

 to glabella. Facial sutures bending sharply outward in front of eyes to cut 

 anterior margin of head-shield nearly at right angles. 



Dimensions. — 



Length of head-shield . . . . 14*0 mm. 



Length of glabella .... 9*0 „ 

 Width of „ at base . . .8*0 „ 



Affinities. — This form resembles P. latifrons in most points, but differs in the 

 pointed apex of the glabella. P. obconicus, Lindstrom, 1 is somewhat similar, but 

 the glabella in it is narrower and not pointed in front, and the pre-glabella portion 

 is smaller. P. acutus, Lindstrom, 2 appears to have a similarly pointed glabella, but 

 the type is a mere fragment. 



Collection. — Mrs. Gray. 



Horizon and Localities. — Mulloch Hill Group (L. Llandovery): Craigens ; 

 ? Mulloch Hill. 



Genus CYPHASPIS, Burmeister. 

 1. Cyphaspis megalops (M'Coy), 184G. 



1846. Harpes ? megalops, M'Coy, Synops. Silur. Toss. Ireland, p. 54, pi. iv, fig. 5. 



1849. Harpidella megalops, M'Coy, Aim. Mag. Nat. Hist. [2], vol. iv, p. 412. 



1852. Harpidella megalops, M'Coy, Synops. Brit. Pal. Foss. Wooclw. Mus., pp. 143, 368. 



1853. Cyphaspis megalops, Salter, Mem. Geol. Surv., dec. vii, pi. v, figs. 1 — 7 (non fig. 8). 

 1867. Cyphaspis megalops, Murchison, Siluria, 4th ed., p. 235, Foss. 65, fig. 2. 



1873. Cyphaspis megalops, Salter, Cat. Cainb. Silur. Foss. Woodw. Mus., pp. 77, 133. 



1877. Cyphaspis megalops, Woodward, Cat. Brit. Foss. Crust., p. 34. 



1879. Cyphaspis megalops, Nicholson and Etheridge, Mon. Silur. Foss. Grirvan, fasc. ii, p. 140. 



Specific Characters. — "General form convex, truly ovate; extremities obtuse. 

 Head-shield very convex, strongly granulose, nearly semicircular, but contracted 

 at posterior angles just in front of genal spine. Genal spine strong, curved, about 

 equal in length to head, reaching back to seventh thoracic segment. Glabella very 

 convex, parallel-sided or parabolic, rounded ; about one third the width of the 

 head and about two thirds its length; with one pair of lateral lobes at base of 



1 Lindstrom, op. cit., p. 78, pi. xv, figs. 22 — 24. 



2 Lindstrom, op. cit., p. 79, pi. xv, fig. 25. 



