322 Reports and Proceedings. 



of chemical composition, and not to infiltration of foreign matter at 

 the time of metamorphism. (3) That the highly alkaline portions 

 of the strata have been most susceptible to change. (4) That in 

 beds having the same composition, but exhibiting various degrees of 

 alteration, the intensity of the metamorphism has been in direct 

 proportion to the amount of water present in the strata. (5) That 

 in some places the rocks have been reduced to a pasty condition. 



3. "On a Cheirotherian Footprint from the base of the Keuper 

 Sandstone of Daresbury, Cheshire." By W. C. Williamson, Esq., 

 F.K.S., Professor of Natural Histoiy, Anatomy, and Physiology 

 in Owens College, Manchester. Communicated by the Assistant 

 Secretary. 



The specimen in question was discovered by Mr. J. W. Kirkham, 

 in the Lower Keuper Sandstone at Daresbury Quarry, It differs 

 from all footprints hitherto obtained from this district, in being 

 more quadrate, and distinctly that of a scaly animal ; the separated 

 toe is also less recurved, and approaches nearer to the other toes. 

 The arrangement of the scales corresponds very closely with that 

 seen in the foot of the living AlHgator ; many of them run across the 

 foot in oblique lines, as is common amongst living Crocodilians, 

 leaving no room to doubt that they represent true scales, and not 

 irregular tubercles, such as are seen on the skin of some Batrachians. 

 Traces of other impressions of feet occur on the slab, particularly an 

 imperfect one with much larger and more oblong scales, especially 

 under the heel ; and this difference is so very similar to what is seen 

 in the fore and hind feet of many Saurians, that Prof. Williamson 

 believed that they did not belong to a Batrachian animal at all, but 

 that they were Saurian, if not Crocodilian, in every feature. 



4, "A description of some remarkable 'Heaves' or Throws in 

 Penhalls Mine." By J. W. Pike, Esq. Communicated by Dr. C. 

 Le Neve Foster, B.A., F.G.S. 



This mine is situated in the parish of St. Agnes, in Cornwall, 

 and is, from the extraordinary dislocations and heaves of the lodes 

 and veins, without a parallel in any other part of the county. In 

 the immediate neighbourhood of the workings, taking the well- 

 known law that a lode or vein traversed is older than the one tra- 

 versing it, there are in the order of formation, (1) four or five tin 

 lodes, (2) three or four "Downright" lodes, (3) innumerable 

 "gossans," (4) a great number of slides or faults, dijDping at various 

 angles, (5) four cross courses, and (6) certain caunting slides. 

 The mineral productiveness of the tin lodes is increased by the 

 proximity of the gossans, but not by that of the slides ; and 

 although the dislocations are most perplexing to the miner, the 

 district has yielded great riches, and has been worked from time 

 immemorial. 



The following specimens were exhibited : — 1. A Cheirotherian 

 Footprint from the base of the Keuper at Daresbury, Cheshire ; 

 exhibited by J. W. Kirkham, Esq. 2. Specimens of Gold from 

 Nova Scotia, and Silver Ores from South America ; exhibited by 

 Prof. J. Tennant, F.G.S. 



