144 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



son in Britain, Hall in America, and Barrande in Bohemia, upon 

 the history, morphology, and distribution of the Rhabdophora 

 through the Lower Palaeozoic rocks of Britain, Europe, and North 

 America, have greatly added to our knowledge of their stratigraphical 

 value and distribution both in time and space. To no author, how- 

 ever, are we so much indebted as to Mr. Lapworth for his exhaustive 

 researches in this department of Palaeontology. Until his careful 

 analysis and descriptions of the Rhabdophora, as well as the physical 

 relations, of the Moffat series in Scotland, and his able papers in the 

 Ann. & Mag. Nat. Hist. ser. 5, vols, iii.-vi., we had little clear know- 

 ledge either of their zoological grouping or stratigraphical distribution 

 and relations to other geographical areas, either in Britain, Europe, 

 or America. That the southern Highlands or uplands of South Scot- 

 land yield rocks of a peculiar character is well known. They consist 

 of two t3 r pes — coarse greywacke, grey, green, or purple in colour, 

 associated with fissile flagstones, which either alternate with the grey- 

 wacke, or are arranged separately in zones of considerable thickness. 

 These two types preponderate. " On the west coast, near Girvan, 

 limestones, shelly sandstones, and mudstones yield fossils in great 

 profusion, and both mineralogically and palaeontologically remind us 

 of the most prolific areas of Wales and Shropshire." 



Certain beds of black carbonaceous shales and mudstones occupy- 

 ing " long lenticular areas occur in the great mass of barren grey- 

 wacke ; they form extended moniliform lines of great extent, and 

 range at intervals throughout the northern half of the Southern 

 Uplands, from the Irish Channel to the North Sea ; these black 

 shales everywhere swarm with Rhabdophora." It is this group of 

 Graptolitiferous strata of the south of Scotland (the Moffat series), 

 and their physical and zoological relations to deposits in other areas, 

 that Mr. Lapworth has made classical. We know of few or no Lower 

 or Upper Llandovery Hydrozoa in Wales. The Coniston Mudstones 

 (Westmoreland) yield 6 genera and 25 species ; and these probably 

 belong to the Lower Llandovery series. The value, however, of the 

 Scotch deposits, and their Graptolitic fauna of 50 or more species, is 

 very great ; they clearly show us that the paucity of species in 

 the Welsh rocks is probably due to geographical and other physical 

 changes. 



South of Westmoreland this group had scarcely a representative 

 after the deposition of the Caradoc, none having survived the close 

 of the Upper Bala period ; for the Lower Llandovery in North Wales 

 has yielded few or no species ; the Upper Llandovery and the suc- 

 ceeding Wenlock group, through the Tarannon beds, 5 genera and 

 23 species ; North Wales 4 genera and 8 species, and South Wales 

 8 genera and 11 species ; Westmoreland 3 genera and 12 species ; 

 Ireland none. These several numbers are as near as I can bring 

 them, knowing the difficulty of understanding the Llandovery ques- 

 tion, and omitting in North Wales the sandy or arenaceous Llan- 

 dovery, which (in that area) does not appear to have furnished a 

 congenial habitat for the growth and development of the Rhabdo- 

 phora. Highly favourable, however, the conditions seem to have 



