WORK ON THE PALAEOZOIC ROCKS. 99 



older rocks, we find here foliated and massive hornblendic, 

 pyroxenic and micaceous rocks, quartz rocks and quartz 

 schists, limestones and graphite schists included in the 

 Wend under the name of " Lewisian Gneiss". These are 

 interbanded with long strips of epidiorite running in a 

 general north-west and south-east direction, and the whole 

 succeeded unconformably by the " Torridonian " group, 

 which the surveyors divide into a division of grey grits, 

 dark shales, and breccias, and another of coarse red and choco- 

 late grits. Lastly, Professor Bonney contributes a paper 

 (5) on general questions concerning the formation of gneiss, 

 in which are remarks bearing upon the formation of, or 

 the occurrence of changes in, the rocks of Twthill (Caer- 

 narvon), Llanfaelog (Anglesea), the granite of St. Davids, 

 the " Hebridean " rocks and Torridon sandstone of Scotland, 

 and of rocks referred by some to the Precambrian, those 

 of the Lizard district and of Guernsey. 



2. Lower Palceozoic Rocks. 



Contributions to the history of these rocks have been re- 

 ceived from Cornwall and the northern part of England. In 

 the former area Mr. F. Stephens maintains (6) that the rocks 

 of the Marazion and Perranuthnoe districts, like those of St. 

 Just, "must be considerably older than the strata of Camborne 

 and Falmouth, possibly very early Cambrian," though no evi- 

 dence appears in the paper in support of this view. A 

 more important paper referring to the old rocks of this country 

 is by Mr. Teall (7), who describes the occurrence of spher- 

 oidal greenstones with radiolarian cherts (these cherts 

 occur both on Mullion Island, where they have been pre- 

 viously recorded in the publications of the Geological 

 Society of London, and on the mainland in the Gorran and 

 Veryan districts, where they have been subsequently 

 detected by Mr. Howard Fox). On the mainland these 

 cherts have been ascertained apparently to underlie the 

 Caradoc quartzites. Mr. Teall mentions the record by 

 Rothpletz of similar radiolarian cherts in Saxony associated 

 with spheroidal diabases, and a similar association of ig- 



