Yol. 55.] BEDDED ROCKS OE COUNTY WATERFOED. 749 



to some individuals of the very variable species Ch. exsul^ Beyr.^ 

 which occurs in the Echinosphserite-limestone Ci of Eussia and the 

 ■equivalent beds of Scandinavia. 



Phacops Jamesii, Portlock. 



This species does not appear to have been recorded outside 

 Ireland. Its original discoverer ^ records it from the ^ Silurian 

 schists of Tramore, County Waterford.' Salter^ records it from 

 ^ Newtown on the Suir,' and in his monograph * from Tyrone as 

 well. The Geological Survey Memoir on the Waterford area 

 frequently confuses this species with Ph. Brongniarti^ as I have 

 previously mentioned elsewhere.' It is characteristic of Stage 2 of 

 the Tramore Limestones, and is especially abundant at Quillia and 

 Pickardstown. In the upper beds (Stage 3) its place is taken by 

 Ph. Brongniarti. I have nothing to add to Salter's description 

 of the species, except that some individuals have the front slightly 

 pointed, as in the supposed male form of Ph. Brongniarti.^ 



Schmidt "^ is inclined to place Ph. Jamesii and Ph. Brongniarti in 

 the subgenus Pterygometopus, which is especially characteristic of 

 Stages Bs & Ci in Russia. Ph. scleroj^s (Dalm.) is the type of 

 this subgenus, but Ph. Jamesii is certainly most nearly allied to those 

 members of it which are transitional to Chasmops. So far as the 

 characters of the glabella go. Ph. Jamesii bears the closest resem- 

 blance to Ph. ingrica, Schmidt (op. cit. p. 95 & pi. ii, fig. 16), which 

 occurs in the Echinosphaerite-limestone C i and is one of these 

 intermediate forms. 



Phacops Brongn^iarti, Portlock. 



Unlike Phacops Jamesii, this species has been recognized in various 

 localities in the British Isles. It is readily distinguished from 

 Ph. Jamesii by the larger eyes and characters of the glabella, but, as 

 above stated, it has been confused with it in the Survey Memoir, 

 so that the species Ph. Jamesii does not appear in the list. 

 Ph. Brongniarti appears also to mark a slightly higher horizon 

 ihan Ph. Jamesii, for it is most abundant in the upper beds in 

 Newtown Cove, while it is rare (or absent ?) in Stage 2 of these 

 limestones. Schmidt '^ compares this species with his Ph. trigono- 

 cephala from the Orthoce7'as-limestone B 3, but it seems to me to 

 be more allied to some of the higher forms which pass into 

 Chasmops, and are specially characteristic of the higher stage C i in 

 Russia. 



^ Schmidt, 'Eev. Ostbalt. Silur. Trilob.' pt. i, Mem. Acad. Imp. Sci. St. 

 Petersb. ser. 7, vol. xxx (1881) No. 1, p. 137, and references to Ch. exsul and 

 its subspecies. 



2 Portlock, ' Kep. Geol. Londond.' 1843, p. 283. 



3 Geol. Surv. Mem. dec. vii (1853) No. 1, p. 10. 



* Monogr. Palaeont. Soc. ' Brit. Trilob,' 1864, p. 32. 



' Geol. Mag. 1897, p. 505. 



^ Salter, Monogr. Palaeont. Soc. ' Brit. Trilob.' 1864, p. 35. 



"^ ' Eev. Ostbalt. Silur. Trilob.' pt. i (1881) p. 62. 



« Ibid. p. 81. 



