no PEOCEEDINGS OF THE GEOLOGICAL SOCIETY, 



the western margin of the Ashby-de-la-Zouch Coalfield. These 

 pebbles, which are collected for sale and used as " burnishers " (for 

 which their extreme hardness qualifies them) vary from a diameter 

 of -j-\)- inch to the size of a man's fist. They present many 

 varieties of form, usually rounded and often very smooth, angular, 

 and subangular ; a few contain cavites, which are often lined with 

 fibrous botryoidal ore, or contain a group of crystals of calcite, or a 

 kernel of soft pea-ore ; have sometimes an agate-like, and rarely a 

 columnar structure, and occasionally exhibit well-marked magnetic 

 polarity, others being simply magnetic. Sometimes they show 

 dimpling, also grooving and striation resembling those produced by 

 ice-action, whilst at other times they seem to have been crushed 

 and re cemented ; many of these markings are doubtless due to oscil- 

 latory movement of the rocks en masse. Many of these pebbles 

 contain fossils of various kinds, chiefly plant- and insect-remains, 

 but with a few of Annelids, Mollusca, and Fish (?). All the fossils are 

 of Carboniferous age (Coal-measures, for the most part). Amongst 

 the associated rock-fragments in the breccias many bits exhibiting 

 cone-in-cone structure occur, composed chiefly of a close-grained 

 quartzose material ; and a specimen showing the cones whose axes 

 lie in radiating lines (the cones facing upwards, downwards, and 

 sideways or fan-shaped) has been noticed for the first time. 



From the consideration of all the facts detailed in the paper, the 

 Author concluded that the nodules were originally composed of 

 clay-ironstone, and that they were derived from the Coal-measures, 

 whilst other fragments were possibly of older date. He considered 

 that the pseudomorphic action by which they have acquired their 

 present composition must have taken place in situ since their inclusion 

 in the breccia. 



Discussion. 



The Pkesident believed, from a study of the specimens in the 

 Jermyn-Street Museum, that there was no evidence of the action of 

 ice in the Permian breccias to which allusion had been made by the 

 Author, but that the striation of the fragments, like the dimpling 

 and crushing in the pebbles of more than one conglomerate, were 

 due to movements of the rocks. 



Prof. Hughes regretted the absence of specimens. He could 

 not understand the identity in miner alogical character of the pebbles 

 with fossils, and of those with cone-in-cone structure. 



The following specimens were exhibited : — 



A specimen showing the clavicles and inter-clavicle of Iguanodon, 

 in situ, exhibited by J. W. Hulke, Esq., F.E.S., Y.P.G.S., in illustra- 

 tion of his paper. 



Palaeozoic fossils, exhibited by J. E. Marr, Esq., E.G.S., and 

 T. Eoberts, Esq., F.G.S., in illustration of their paper. 



