Yol. 55.] BEDDED BOCKS OP COUNTY WATERFOED. 761 



allied forms. Orthisina is a characteristic genus of the Lower 

 Ordovician of Kussia and Scandinavia.^ The Waterford form of 

 0. crispa is very variable, and possibly comprises more than one 

 species. A subquadrate, subglobose variety from Knockmahon, with 

 flattened lateral angles and almost obsolete concentric markings, is 

 figured by Davidson.^ Another with a weak sulcus in the ventral 

 valve and considerably flattened (Davidson, op. cit. fig. 8) has a 

 finer ornamentation than is usual in the Tramore specimens 

 (Davidson, op. cit. fig. 5). 



POEAMBONITES INTERCEDENS, Var. EILOSA (M'Coy). 



Davidson^ discussed this species at length, and mentioned its 

 sole undoubted places of occurrence in the British Isles as Duna- 

 brattin, Tramore, and Knockmahon. I have found it in consider- 

 able abundance in the lower portion of the Tramore Limestones 

 on the west side of Dunabrattin Head, and there are specimens 

 in the Geological Survey Collections at Dublin from the beds 

 near Tramore. The specimens from Wrae Quarry, Peeblesshire, 

 were considered doubtful by Davidson. P. intercedens, together 

 with several others of Pander's * species of the genus, was put by 

 Eichwald ^ into Schlotheim's species P. cequirostris, but neither 

 Davidson nor De Yerneuil considered Eichwald's synonymy correct. 

 It is, however, clear that Davidson did not use the specific name 

 in the limited sense in which Pander had done, as a comparison 

 of the Irish specimens with Pander's figures at once shows. 

 Schmidt ^ records P. intercedens, Pander, from the Orthoceratite- 

 limestone (Yaginatenkalk), B 3 ; but it is not stated whether he uses 

 the name in the extended sense. P. cequirostris (Pander), which 

 may be compared with our form, is stated by the same author '^ to 

 occur in the Echinosphserite-limestone, C 1. 



Brogger ^ thinks that the Irish form may be a separate species, 

 but the variety of P. intercedens (Pander) which he figures from 

 the Orthoceras-limestojie bears an extremely close resemblance to 

 the specimens from Dunabrattin Head. M'Coy's ^ type-specimen, 

 which I have examined, came from the ' schists at Knockmahon, 

 Tramore, County Waterford.' There is a valuable discussion of 

 the affinities of the genus in a paper by Noetling,^° and in Hall & 

 Clarke's" great work on the Brachiopoda. 



1 Freeh, ' Leth. Geogn.' pt. i, vol. ii (1897) p. 73. 



^ Monogr. Palaeont. Soc. ' Brit. Silur. Brach.' vol. iii, p. 256 & pi. xxxviii, 

 fig. 6. 



3 Ihid. p. 195. 



4 ' Beitr. z. Geogn. Kuss. Eeich.' 1830, p. 95. 

 ^ ' Leth. Ross.' 1860, p. 794. 



6 ' Rev, Ostbalt. Silur. Trilob.' pt. i, Mem. Acad. Imp. Sci. St. Petersb. 

 ser. 7, vol. xxx (1881) No. 1, p. 21. 



■^ Cuart. Journ. Geol. Soc. vol. xxxviii (1882) p. 521. 



8 ' Die Silur. Etagen 2 u. 3,' 1882, p. 50 & pi. xi, figs. 1 a-d. 



9 ' Syn. Silur. Foss. Irel.' 1846, p. 39 & pi. iii, fig. 28. 



10 Zeitschr. Deutsch. Geol. Gesellsch. vol. xxxv (1883) p. 355. 



11 Palaeont. N. Y. vol. viii (1894) Brach. pt. ii, p. 225. 



Q. J. G. S. No. 220. 3 d 



