EDINBURGH Royal Society, July 1. ALAN W. MOZLBY: The freshwater and terrestrial mollusca of Northern Asia: A critical and detailed study of sixty-seven species and sub-species of non-marine mollusca from Siberia, fifty being aquatic and seventeen terrestrial. They are of four categories: (i) those common to Europe and Asia; (ii) those that are circumboreal: (iii) those common to north-east Asia; and (iv) those endemic to Siberia. The various habitats are described. From the point of view of molluscan distribution, four faunal regions are recognised: (i) the great Siberian region; (ii) the Baikal region (this is rich but so peculiar and specialised that it falls outside the scope of the present paper); (iii) the far eastern region; and (iv) the Chuckchee-Kamchatka peninsula. S. M. K. HENDERSON: Ordovician submarine disturbances in the Girvan district. The Ardwell Beds, a series of greywackes of Lower Caradoc age in the Girvan district of Ayrshire, contain intraformational breccias and slip-bedding; grading, with accompanying minor current bedding, is common throughout. The disturbed bands rarely exceed three inches and show an eroded upper surface, especially clear in examples of slipping. In the case of breccias, submarine earthquakes loosened and broke up the sea floor sediment; resultant tunamis tore up and distributed the debris. Sediments of a more plastic nature slid down submarine slopes. A boulder bed has likewise been attributed to the slipping of sediment down a submarine slope. MABY G. CALDEB: Further observations on the genus Lyginorachis, Kidston. Three new species of the fossil genus Lyginorachis are described, namely, L. Waltoni, L. Brownii and L. trinervis. The specimens are all from rocks of Calciferous Sandstone age in the west of Scotland, L. Waltoni being from Arran and L. Brownii and L. trinervis from the Kilpatrick Hills. Some additional notes are also made on Lyginorachis taitiana, from specimens in the Kidston Collection of Fossil Plant Slides. STEWABT MAC-LAGAN and EDWABD DUNN: The experimental analysis of the growth of an insect-population. Experiments with the rice weevil (C. oryzce) have shown that a population of these beetles offers a certain internal resistance to its own growth. This is effected through a decrease in the copulation frequency, fecundity and fertility of the adults, with increasing density; and an increase in larval mortality. The behaviour of the beetles is entirely irrational, the limitation of population growth being brought about by influences which are primarily thigmotropic. So precise is the relationship between the population density and the copulation frequency of the beetles that it can be described by the equation Y = a × b, where Y represents copulation frequency and X the population density (see also NATUBE, Jan. 5, p. 33). T. M. MAOROBEBT: Some series and integrals involving associated Legendre functions, regarded as functions of their degrees. Legendre functions and products of Legendre functions in finite integrals and series are replaced by the corresponding Mehler-Dirichlet integrals; the resulting formulae are then expressed as Dirichlet integrals, and the limits of these integrals give the values of infinite integrals and series.