ANNIVERSARY ADDRESS OF THE PRESIDENT. 



79 



of the Alum slates of Sweden and Norway, which holds the same 

 position there as in our own area.) 



The second division or upper part of the Lower Lingula-flags of 

 Salter (the typical Lingula-flags) are finely developed in North Wales, 

 near Tremadoc andEfestiniog, atMaentwrog, Borth, Marchllyn-Mawr, 

 Llanberris, Carnedd Efiliast, Dolgelly, and Trawsfynydd. Cruziana 

 semiplicata, Hymenocaris vermicauda, Olenus micrurus, Lingulella 

 Davisii, and Microcliscus are the leading types of this upper part of 

 the lower series. Physically these are hard, grey, thick, sandy 

 beds and flags. 



The Upper Lingula-flags of Salter differ essentially from the Lower 

 Division, consisting of dense black pyritous slates, or black slates with 

 pyritous bands near the base, with a large fauna differing almost en- 

 tirely from that of the Lower Lingula-flags ; for out of 35 species oc- 

 curring in the lower group, only 5 pass from the lower to the upper — 

 namely Agnostus princeps, Microcliscus punctatus, Lingulella Davisii, 

 L. lepis, and Obolclla sagittalis, and this in the same district. At 

 Tremadoc, Maentwrog, and west of Ffestiniog the beds are rich in 

 fossils — Olenus alatus, 0. scaraboeoides, Agnostus princeps, Conoco- 

 ryphe clepressa, C. invita, Orthis lenticularis, and Dictyonema thickly 

 crowding the beds. 



It is well known that in 1851 Barrande visited England pur- 

 posely to compare his fine series of fossils with our types, when he 

 at once recognized the " Lingula-flags " of Sedgwick as the precise 

 equivalent of his primordial stratum (Etage C). Barrande also 

 carried out his comparison and correlation not only with the fauna 

 of our country, but also between those of the European and American 

 continents, with what success the literature and progress of geological 

 science has shown. 



The comparison of the Arenigs of Shropshire (Stiper stones) and 

 Westmoreland (Skiddaw) will form an important feature for our 

 consideration. 



The close analyses of the Lower and Upper Lingula-flags must be 

 taken separately. The faunas of the two differ remarkably; and only 

 8 species connect them — namely 5 species of Trilobita (Asaphus 

 princeps, A. trisectus, A. Salteri, Microcliscus punctatus, and Para- 

 doxides Hicksii) and 3 of Brachiopoda {Lingulella Davisii, L. lepis ; 

 and Orthis sagittalis). The Middle Lingula-flags of some authors con- 

 tain also only 5 species : — 1 Trilobite, Oonocoryphe bucephala, Belt ; 

 3 Brachiopoda, Kutorgina cingulata, Belt, Lingula squamosa, Holl, 

 and Lingidella Davisii ; with Bellerophon cambrensis, Belt. Two 

 of the five species appear to be confined to this horizon, viz. Lingula 

 squamosa and Bellerophon cambrensis. This fauna is too small to 

 be of any value for our present purpose. 



Plants. — No trace of any kind. 



Protozoa. — The sponge Protospongiafenestrata, Salt., passes up from 

 the Menevian and Harlech beds at St. David's to the Lower Lingula- 

 flags. This species has the longest range of the four known forms ; 

 but none of the four ranges higher. 



