418 MISS E. M. R. WOOD ON THE LOWER LUDLOW [May 10)00^ 



In 1880 Prof. Lapworth, in his brilliant paper on the ' Geological 

 Distribution of the Bhabdophora,' 1 grouped the Lower Ludlow as 

 his ' zone of Monograptus Nilssoyii ' and described it as the ' highest 

 and most important graptolitic zone of the Wenlock-Ludlow 

 formation.' He noted that its collective fauna is ' specifically very 

 distinct from that of the Wenlock Shales,' and suggested that the 

 formation ' will probably in the future be found divisible into several 

 distinct zones.' 



In 1883 Tullberg, 2 in the great work embodying his researches 

 on the graptolites and graptolite-bearing rocks of Scania, recognized 

 the Carcliola-Skiffev as his highest graptolitic zone and correlated 

 them with the Lower Ludlow Beds of Britain. 



In 1885 Prof. Watts 3 recorded the occurrence of graptolites of a 

 Lower Ludlow type in the strata of the Long Mountain. Pive years 

 later 4 he gave a broad zonal subdivision of these beds by means 

 of their graptolites. His paper marks an important advance in our 

 knowledge of the Lower Ludlow Beds in general, since he recognized 

 two lithological horizons above the Wenlock Shales, each charac- 

 terized by some distinctive graptolites, namely : — 



(2) An Upper Group of hard thick flags with occasional shales, yielding 



Monograptus leintwardinensis, M. Salweyi, and M. Bcemeri. 



(1) ALower Group of thin muddy shales with rare flaggy ribs, containing 



M . colonus, M. Nilssoni, and Cardiola interrupta. 



In 1892 Mr. Marr 5 published the results of his investigations on 

 the Ludlow rocks of the Lake District. In this paper, as in that 

 on the Stockdale Shales, he utilized graptolites as his characteristic 

 zonal fossils. As this is the most important piece of research 

 hitherto attempted in the zonal division of rocks comparable with 

 the Lower Ludlow Beds, it may be as well to tabulate here his 

 succession in descending order : — 



(5) Bannisdale Slates = zone of Monograptus leintwardinensis and con- 

 taining M. colonus and M. Salweyi. 

 (4) Coniston Grits = zone of M. bohemicus (upper part) with two inter- 

 esting fossil horizons : — 



(2) Sheerbate Flags with M. colonus, M. bohemicus, and M. RcemerL 

 (1) Winder Grit. 



(3) Upper Coldwell Beds = zone of M. bohemicus t (lower part) with 



M. colonus, M. Roemeri, and M. bohemicus. 



(2) Middle Coldwell Beds = zone of Phacops obtusicaudatus. 

 (1) Lower Coldwell Beds = zone of Monograptus Nilssoni. 



He considered that the Wharf e Grits represent the Lower or 

 Middle Coldwell Beds or both, and that the Moughton Whetstones 

 occurring below them and containing M. dubius, M. Nilssoni, and 

 M. uncinatus? belong probably to the Lower Coldwell horizon. 



In the same year Dr. Barrois published his memoir on the ' Distri- 

 bution des Graptolites en Prance.' 6 He recorded many species, now 



1 Ann. & Mag. Nat. Hist. ser. 5, vol. vi, p. 201. 



2 ' Skanes Graptoliter ' pt. ii, Sver. Geol. Undersokn. ser. C, no. 55. 



3 Quart. Journ. Geol. Soc. vol. xli, p. 532. 



4 Brit. Assoc. Rep. 1890 (Leeds) p. 817. 



5 Geol. Mag. pp. 536 et seqq. 



6 Ann. Soc. Geol. Nord, vol. xx, p. 75. 



