234 Reports and Proceedings — Geological Society of London. 



Hard Bed of the Lower Coal-measures. Most leaves were very small, 

 being only 1-2 mm. long and '8-1 mm. broad. They are falcate in 

 shape, and were borne on slender twigs in alternating whorls of four. 

 The structure of these slender twigs differs somewhat from that of the 

 young Calamitean stems already described by Williamson and others, 

 but it may be compared in some features with the structure of the 

 young stems of some modern Equisetums. 



The tissues of the small leaves show a concentric arrangement. 

 In the centre there is a vascular bundle consisting of four or five small 

 tracheides, surrounded by thin-walled elongated cells. The bundle is 

 surrounded by a zone of cells with dense black contents, termed by 

 Hick the melasmatic tissue, and is probably comparable with the 

 bundle-sheath of the leaves of modern plants. The cells of the 

 palisade-like assimilating tissue abut on to this ; they have large 

 spaces between them. The epidermis is thinner on the concave side 

 of the leaf, and the stomata are situated on this face only. The latter 

 are characterized by transversely striated guard-cells, similar to those 

 seen in many species of modern Equisetums. These leafy twigs seem 

 to be identical with the impression species Calamocladus charaformis 

 (Sternb.) ; their structure seems to indicate that they grew in 

 a pendulous manner. Specimens have been obtained showing variations 

 in structure from the normal type. 



Pour other types of leaf have been discovered differing in size and 

 in arrangement of tissues. In all of these there is a very conspicuous 

 strand of sclerenchymatous fibres running up the adaxial side of the 

 leaf, and forming a large part of its apex. These fibres become more 

 conspicuous in the longer leaves. In some types the thin- walled 

 (phloem) tissue of the bundle is much reduced, or even absent. The 

 melasmatic tissue also varies considerably in amount. Some of these 

 longer leaves were probably identical with C. grandis (Sternb.); 

 others with C. equisetiformis (Schloth.). They are characterized by 

 a more compact structure, with smaller and fewer intercellular spaces. 



The structure of the smaller leaves probably indicates that they 

 grew in a moist situation, or where the atmosphere was humid. The 

 larger leaves are more xeromorphic in character. The results 

 obtained from this work indicate that the Calamites were truly 

 microphyllous. 



II. — Geological Society of London. 



1. March 8, 1911.— Professor W. W. Watts, Sc.D., M.Sc, F.R.S., 

 President, in the Chair. 

 The President announced that the Council had awarded the 

 proceeds of the Daniel Pidgeon Fund for 1911 to Tressilian Charles 

 Nicholas, B.A., Trinity College, Cambridge, who proposes to 

 investigate the relations of the older rocks in the Lleyn Peninsula 

 ( Carnarvonshire). 



The following communications were read: — 



1. "Contributions to the Geology of Cyrenaica." By Professor 

 J. W. Gregory and others. 



