78 TRILOBITES OF GIRVAN. 



Length of glabella . . . .3-5 mm. 



„ of thorax . . . 5*5 „ 



,, of pygidium .... 3*0 „ 



Width of „ . . . 5-5 „ 



,, of axis . . . 2*0 „ 



Remarks. — The description given by Nicholson and Etheridge (op. cit., p. 174) of 

 this species has been slightly amplified above, several minor features having 

 failed to attract their attention. The preceding description is drawn np after 

 a minute examination of the original type specimen. 



In one complete specimen in Mrs. Gray's collection, but not very well preserved, 

 the hypostome is present in its normal position. It is about two thirds the length 

 of the glabella, and possesses a long narrow convex subcylindrical body, more 

 than twice as long as wide, marked by a few strongly arched lines near the front 

 end. Towards its posterior extremity at about two thirds its length its sides are 

 indented by short oblique notches, and its rounded extremity has a flattened band 

 pressed against it. Near the front end the border is extended as a pair of flattened 

 rounded (?) wings ; and a narrow raised rim lies at the front end of the body. 



Affinities. — This species is closely allied to P. girvanensis, but it differs not only, 

 as Nicholson and Etheridge have pointed out, in its more elongate shape and 

 narrower glabella, but in the course of the facial suture and the more forward 

 position of the eyes, which also are relatively smaller. 



Collections. — Mrs. Gray (f. M.) ; Museum of Practical Geology ; Edinburgh 

 Museum. 



Horizon and Localities. — Drummuck Group (U. Bala): Thraive Glen; 

 Drummuck. 



4. Proetus pseudolatifrons, sp. nov. Plate XI, figs. 7 — 9. 



1848. Proetus latifrons, Salter, Mem. Geol. Surv., vol. ii, pt. 1, p. 337, pi. vi, figs. 1, la. 



1854. Forbesia latifrons, M'Coy, Synops. Brit. Pal. Foss. Woodw. Mus., p. 174. 



— Proetus latifrons, Morris (e. p.), Cat. Brit. Foss., 2nd ed., p. 114. 



1872. Proetus latifrons, Murchison, Siluria, 5th ed., p. 235, Foss. 65, fig. 7. 



? 1873. Proetus latifrons, Salter, Cat. Camb. Silur. Foss. Woodw. Mus., pp. 134, 1G5. 



1877. Proetus latifrons, Woodward (e. p.), Cat. Brit. Foss. Crust., p. 56. 



1879. Proetus latifrons, Nicholson and Etheridge, Mon. Silur. Foss. Girvan, fasc. ii, p. 171. 



1899. Proetus latifrons (e. p.), Mem. Geol. Surv., Silur. Rocks Brit., vol. i, Scotland, pp. 524, 673. 



Sjiecific Characters. — " Oval; width three fifths the length; gently convex; head 

 and body equally long ; axis prominent, rather narrow ; glabella smooth, widest and 

 most convex behind, as wide as the cheeks, not reaching to the tumid margin ; eyes 

 close to it, large, not prominent ; facial suture vertical from the eye till close to the 

 neck margin, then turning abruptly outwards to the first third ; spines thick, 



