554 Maw — Cambrian Rocks of Llanberis. 



altered to a pale green in the same way as that adjacent to the intrusive 

 dykes of greenstone. The dark green bands were found on analysis 

 to exhibit a totally different composition to that of the slaty matrix, 

 and appeared to have been derived from a different source. With 

 reference to the condition of fusion, under which the dykes of green- 

 stone were intruded, judging from the kind of alteration produced 

 in the adjacent slate, the heat could not have been sufficient to 

 effect a purely vitreous liquefaction of the traps ; and experiments 

 proved that the slaty matrix was fusible at a temperature at which 

 the greenstone remained refractory. 



Vn. — On the Alteration of the Coast Line of Noeeolk. 

 By J. Wtatt, F.G.S. 



THIS paper described the result of observation on the changing 

 coast line of Norfolk. The author showed that the geological 

 changes ia this part of the island were not all to the loss of the 

 nation, proving that in West Norfolk there was a continual addition 

 to the area. A secondary object of the paper was to enforce the 

 necessity of accurate records of the changes of coast lines, and the 

 author suggested that this should be undertaken by a responsible 

 department of the Government, who should combine the two systems 

 adopted by the Ordnance and Admiralty Surveyors, 



YTTT . — Eepokt on Dredging among the Shetland Isles. By 

 J. GwTN Jeffreys, F.E.S., F.L.S., F.G.S. 



THIS, the fourth report by Mr. Jeffreys on dredging in the British 

 seas, as usual contains observations of much interest. Five 

 species are added to the list of British Mollusca, namely, Terebra- 

 tella Spitzhergensis, Dav. ; BhyncJionella psittacea, Gm. ; Leda pernula, 

 Mull. ; SipJionodentalivm Lofotense, Sars. ; and Gadulus subfusiformis, 

 Sars. ; and more information is gained on the geographical distribution 

 and habits of the Mollusca. A list of species obtained from a depth 

 of 170 fathoms is given, of which sixteen were living, and thirty- 

 eight dead. The shells were of the usual tints; the notion that 

 colour is absent, or fainter in shells from deep water appeared to be 

 quite unfounded. Eelics of the Glacial epoch occurred in 170 

 fathoms, and higher, up to 80 fathoms; they were — Pecten Islandicus ; 

 Tellina calcaria; Mya truncata, var. Uddevallensis ; Saxicava rugosa, 

 var. Uddevallensis ; Molleria costulata ; and Trochus cinereus. 



In dredging at a depth of about eighty-five fathoms, on a soft, sandy 

 bottom, twenty-five miles north-north-west of Unst, the canine tooth 

 of an animal of the weasel tribe — probably a ferret — and the shoulder- 

 blade of a bat were brought up. The author is indebted to Mr. 

 Boyd Dawkius for an examination of these remains. 



