PEOETUS STOKESL 79 



vertical, reaching the fourth or fifth segment; axis of body narrow and prominent; 

 fulcrum at half in front, one third behind; caudal axis six- or seven-ribbed, 

 prominent, long conical, only four fifths the length of the semicircular shield, and 

 narrower than the sides, which have about five furrows not reaching the border, 

 with faint ones between them " (Salter). 



Remarks. — It does not appear that the specimens described and figured by 

 Salter (pp. cit.) as " Proetus latifrons (M'Coy) " from the Upper Ludlow of Usk are 

 really identical with M'Coy's Forbesia [Proetus] latifrons from the Silurian of 

 Eggool, co. Mayo. I have compared the type with Salter's figure, and find several 

 important points of difference. In the first place the glabella of Salter's species 

 is more cylindrical, narrower, less triangular, and narrows more gradually and to a 

 less extent towards the front end. Secondly, the pre-glabellar portion is much 

 wider, being nearly one third the length of the glabella, whereas in the Irish type 

 it is very narrow, since the glabella nearly touches the border. Thirdly, the 

 pygidium is longer, more oval, and less transverse, with a narrower, more slowly 

 tapering axis. The fulcrum on the anterior edge also appears to be stronger. 



As previously stated, M'Coy (1854), subsequent to his naming of the Irish 

 specimen Forbesia [Proetus] latifrons, identified with it the Upper Ludlow specimens 

 of Proetus from Underbarrow, Kendal, but they resemble much more closely Salter's 

 form, so far as their poor state of preservation permits one to see. 



Specimens of the head and pygidium agreeing with Salter's species occur in the 

 Upper Llandovery of the Girvan area. The characters are so distinct from those 

 of M'Coy's P. latifrons that it seems absolutely necessary to separate them specifi- 

 cally, and the name P. pseudolatifrons is suggested. 



Collection. — Mrs. Gray. 



Horizon and Localities. — Camregan Group (U. Llandovery): Camregan Wood ; 

 Cuddystone Glen ; Bargany Pond Burn. 



5. Proetus stokesi (Murchison), 1839. Plate XI, figs. 10, 1 I. 



1839. Asaphus stohesii, Murchison, Silur. Syst., p. 656, pi. xiv, fig. 6. 



1845. Proetus stohesi, Loven, Ofv. K. vet. Akacl. Forhandl., p. 50, pi. i, fig. 3. 



1854. Proetus stolcesii, Murchison, Siluria, 1st ed., pi, xvii, fig. 7. 



— Forbesia stolcesii, M'Coy, Synops. Brit. Pal. Foss. Woodw. Mus., p. 174. 



— Proetus stolcesii, Morris, Cat. Brit. Foss., 2nd ed., p. 114. 



1855. Phaetouides stohesi, Angelin, Pal. Scand., p. 22, pi. xvii, fig. 4. 



1873. Proetus stolcesii, Salter, Cat. Camb. Silur. Foss. Woodw. Mus., p. 134. 

 1877. Proetus stolcesii, Woodward, Cat. Brit. Foss. Crust., p. 56. 

 ? 1879. Proetus ? or Acidaspis, Nicholson and Etheridge, Mon. Silur. Foss. Grirvan, fasc. ii, p. 206, 

 pi. xiv, fig. 15. 



