PnOCEKDINGS OF SOCIETIES. 277 



Dicfyoxylony This genus — establislied by the author on stems exhibit- 

 ing structure from the coal-measures — was described as consisting of a 

 central vascular axis, with radiating vascular phites, separated by medullary 

 rays, and surrounded by a pareuciiymatous layer containiug free vascular 

 bundles like those of the centre, and the whole enclosed in a bark com- 

 posed of elongated cells, some of which were thickened by secondary de- 

 posits, and arranged in somewhat regular lozenge-shaped meshes, giving 

 to the exterior of the stem a Lepidodendroid aspect. Five species were 



described. Mr. Carruthers criticized the descriptions of the author, and 



maintained that the stems, though exhibiting certain unimportant varia- 

 tions, could be correlated with the stems of some existing Lycopodiacete. 



W. Carruthers, '' On the Vegetable contents of IMasses of Limestone 



occurring in Trappean Rocks in Fifeshire, and the conditions under which 

 they were preserved." Tiie fragments of limestone had been observed on 

 the shore and traced to their place in the rocks by Mr. Grieve. They oc- 

 curred, of different sizes, in a coarse amygdaloidal trap-rock, and the 

 author believed that they were fragments of a peaty layer forming on the 

 surface of the land at the time the volcanic matter was thrown up, and that 

 this layer was broken up, and its fragments, along with masses of clay, 

 sandstone, etc., were enclosed in the volcanic materials when they were 

 arranged under water. The large amount of lime contained in the trap 

 seized on the peat and converted it into limestone before it had time to 



decay. The plants were those peculiar to the Carboniferous period. 



Professor Williamson believed that the liuicstoue was formed where it was 

 found, and occurred in distinct layers between igneous rocks. The great 

 difference in the hardness of the substance was due to the intluence of the 



burning rock. Mr. Pengelly, in his Re])ort on Kent's Cavern, stated 



that he had obtained impressions of Ftrns in the stalagmite of the Cave, 

 which Mr. Carruthers had determined to be luxuriant specimens oi Pferis 

 aquiUiia. 



Section D. Biology. Depaiitment op Zoology and Botany. — 

 AiKjmt Mil. — Professor AVy ville Thomson, F.R.S., presided, llev. Thomas 

 Brown, F.ll.S.E., " On Fossil Wood from the Base of the Lower Carboni- 

 ferous Rocks at Langton, Berwickshire." The author had obtained from 

 the lower carboniferous rocks of this locality some specimens of fossil 

 wood which seemed to possess certain peculiarities of structure deserving 

 of notice. The transverse section showed a central pith with numerous 

 rays going off" towards the circunderence, and the appearance of annual 

 rings of growth. The longitudinal section showed it to consist of scala- 

 ril'orm tissue, and what appeared to be rays were found to be vascular 

 bundles. The author stated at some length the reasons which led him 

 to think that the dark circles were really analogous to the annual rings of 

 living exogenous trees. He referred also to the combination of crypto- 

 gamic characters with those of exogenous structure. Mr. Carruthers 

 considered that this belonged to a Lepidodendroid ]daid, which had 

 been described by Colta as Diploxyluii. The appearance of annual 

 rings he cousidi'red deceptive, being due to alterations in the speci- 

 mens during fossilization. Professor Thiseltou Dyer, B.A., B.^c, 



"On the So-called ' Minucry ' in Plants." He said, in all large natu- 

 ral families of plants tliere is a more or less distinctly observable 

 general habit or J'uclen, easily recognizable by the practised botanist, 

 but not always as easily to be expressed in words. The existence of 



