Geological Society of London. 283 



author pointed out that there is evidence of a physical break, varying 

 in amount, as well as of a paleeontological one between the Cambrian 

 and Silurian of Scandinavia. Several of the beds of Scandinavia 

 admit of a very exact parallel with strata in the English Lake 

 District. 



The author considered that the fauna of the Scandinavian deposits 

 affords evidence of migrations. This can be shown by observing 

 that the same forms occur in two beds of different age, but are 

 absent from an intermediate one ; or by tracing beds laterally, and 

 showing that the forms occur in an earlier deposit in one locality 

 than in another. 



The author considered the black shales deep-water deposits, and 

 accounted for their wide extent by supposing the material derived 

 directly from the decomposition of the felspar in metamorphic rocks, 

 and so in a very fine state of division. The deep-water fauna in the 

 Cambrian appears to have migrated from the south-west ; the 

 shallow-water forms, as might be expected, were more variable in 

 their direction of migration : examples were given in support of 

 this view. In Silurian times the direction of migration appears to 

 have changed, the disj^ersal taking place from Britain, owing probably 

 to greater local upheaval there. The coast-line also, instead of 

 running in a W.N.W. and E.S.E. direction, seems to have run more 

 W.S.W. to E.N.E., as shallow-water forms are common in Britain, 

 but deep-water forms in the central Swedish area. The result of 

 the author's investigations, as bearing on classification, is that there 

 is a break in Scandinavia at the base of the equivalents of the May- 

 Hill series, but no other break in the Cambrian series of Sedgwick 

 of equal importance : no break, physical or paleeontological, existing 

 at the base of the Ceratop]jge-\\.m.Qs.ionQ (Tremadoc), where some 

 authors have drawn a boundary. 



IIL— April 26, 1882.— J. W. Hulke, Esq., F.R.S., President, in 

 the Chair. — The following communications were read: — 



1. " On Eossil Chilostomatous Bryozoa from Mount Gambier, 

 South Australia." By Arthur W. Waters, Esq., F.L.S., F.G.S. 



The author gave a descriptive list of 66 species of Bryozoa, be- 

 longing to the suborder Chilostomata, from the collection of the 

 Geological Society and of Mr. Etheridge, Jun. ; of these, 15 were con- 

 sidered to be new, 28 are now found living, of which 23 in Australian 

 seas, 25 were found in the material previously described from S.W. 

 Victoria, 2 were considered identical with European chalk forms, 

 11 with Miocene, 12 with Pliocene, and 21 have been found in 

 a collection from Bairnsdale, Gippsland. 



Mr. Waters states that the collections in his hand from S.W. 

 Victoria, Mount Gambier, and Bairnsdale will together yield about 

 200 species of Chilostomata and Cyclostomata. 



2. " Thamniscus : Permian, Carboniferous, and Silurian." By 

 George W. Shrubsole, Esq., F.G.S. 



After a sketch of the genus, represented by one Permian, possibly 

 two Carboniferous, and one Silurian species, the author discussed 



