Cellular Magnesian Limestone of Durham. 387 



Hitchani Street, Ipswich (corroborating the evidence for a deep 

 channel filled with Drift given by the section at St. Peter's Quay, 

 New Mill), Shotley, Stansfleld, and Brettenham Park. The last 

 shows the greatest thickness of Drift recorded in the county, 

 namely, 312 feet. 



2. ' The Cellular Magnesian Limestone of Durham.' By George 

 Abbott, Esq., M.R.C.S., E.G.S. 



The Permian Limestone covers about 1| square miles near Sun- 

 derland; it alternates with beds of marl containing concretionary 

 limestone-balls, and attains a thickness of 65 feet or so. The cellular 

 limestones frequently contain more than 97 per cent, of calcium- 

 carbonate. Magnesium-carbonate occupies the interspaces or 4 cells ' 

 of this limestone, and also the spaces between the balls. The hundred 

 or more patterns met with in it can be arranged into two chief 

 classes, conveniently termed honeycomb and coralloid, each 

 with two varieties ; and each class has four distinct stages, both, 

 classes having begun with either parallel or divergent systems of rods. 

 The second stage is the development of nodes at regular distances 

 on neighbouring rods ; and these in the third stage, by lateral 

 growth, become bands. Einally, in the fourth stage the interspaces 

 become filled up. The upper beds are usually the most nearly 

 solid. In the coralloid class the nodes and bands are smaller and 

 more numerous than in the honeycomb class. In both classes tubes 

 are frequently formed. The rods have generally grown downwards, 

 but upward and lateral growth is common. A section of Eulwell 

 ■Quarry is given. 



December 17th. — Prof. Charles Lapworth, LL.D., E.R.S., 

 President, in the Chair. 



The following communications were read : — 

 1. 'Note on the Magnetite-Mines near Cogne (Graian Alps).' 

 By Prof. T. G. Bonney, D.Sc, LL.D., E.R.S., E.G.S. 



These mines have been worked probably since Roman times, but 

 are now almost deserted. They are situated in the Yal de Cogne, 

 one of the larger tributaries to the Yal d'Aosta from the Graian Alps. 

 The author, in company with the Rev. E. Hill, last summer 

 examined tw 7 o localities w T here the ore has been worked. At 

 one, the Eilon Licone, the mass of magnetite is probably* about 

 80 or 90 feet thick and some five times as long. At the other 

 place, the Filon Larsine, the mass apparently is not nearly so 

 thick. The ore is a pure magnetite, jointed like a serpentine, 

 a thin steatitic film being often present on the faces. At both 

 localities the magnetite is found to pass rapidly into an ordinary 

 serpentine, the transitional rock being a serpentini/.ed variety of 

 the cumberlandite described by Prof. AYads worth in his 'Lithological 

 Studies.' The serpentine is intercalated, like a sill, between two 



