The vogesites are of two distinct types, one of which will be designated type A and the other type B.

For many years composite minor intrusions, both sills and dykes, have been known from various parts of the world and most petrologists must have speculated as to the probable effect produced in the event of such composite intrusions having reached the surface in the form of an effusion. For obvious reasons it has not been found possible to trace a composite dyke upwards into a lava flow. However, during the revision of 1 inch Sheet 30 (Renfrewshire) for the Geological Survey, the author encountered, in the neighbourhood of Inverkip, a small village on the Firth of Clyde south of Greenock, certain peculiar lava flows which are believed to represent the effusive equivalents of composite minor intrusions. These “composite lavas”, which form the main subject of the present paper, are of Lower Carboniferous age (Calciferous Sandstone Series) and occur interbedded among the more normal flows towards the base of the volcanic group. Two distinct rock varieties, one highly porphyritic, with large phenocrysts (up to 1·5 cms. long) of basic plagioclase, and the other non-porphyritic, are associated within the same flow. The porphyritic type always forms the upper part of the flow and overlies the non-porphyritic; the junction shows unmistakable evidence that both were in a fluid state along their mutual contact at the time of emplacement.

During an intensive investigation of the joint phenomena of the South Leicestershire igneous intrusions a widened joint cavity eighteen inches long and five wide apparently filled with “calcite or quartz” was noted. On closer examination the mineral showed perfect trapezohedra of analcime and cube-like rhombohedra of chabazite. The analcime crystals attained a diameter of 0·4 inches: they comprised the bulk of the specimen, the chabazite being very subordinate and only in small sizes. As is usual the analcime had preceded the chabazite in order of crystallization. The cubic mineral was colourless, milky white, and also reddish through impregnation with iron oxide. The chabazite was opaque white but translucent on fracture.

ON the advice of Prof. L. W. Collet, of the University of Geneva, M. E. Bovier has, for several years now, been studying the Liassic deposits in what he terms the “second range” of the Jura Mountains, north of Bellegarde in the Department of the Ain, France. He collected a large number of ammonites in the quarry at Prébasson, near Champfromier, where the Upper Sinemurian is well developed, especially deposits in the oxynotum zone. The stratigraphical details and full lists of fossils have now been published by M. Bovier in a paper entitled “Les Ammonites du Simémurien supérieur de Champfromier (Jura français)”. The object of the present note is merely to direct attention to some facts of importance for the correlation of Liassic deposits, facts that confirm the suspected unsoundness of polyhemeral Liassic chronology. The whole problem of correlation over wider areas is being discussed more fully in connection with higher beds in the Jurassic. M. Bovier compared his ammonites with the Liassic material in the Geological Department of the British Museum, collected in the corresponding Upper Sinemurian beds at Charmouth. For it was Dr. Lang's collection, in the first instance, being the only material available that had been carefully collected, on which the original subzones (within the obtusum zone) were based, as well as the later subdivisions of the oxynotum and raricostatum zones. I ought to make it clear in this connection that the term zone is here used in its original meaning. Thus d' Orbigny in 1850 already spoke of his Kimmeridgian stage as the “zone of Ammonites lallieri, of Ostrea deltoidea and O. virgula,” while Oppel, six years later, wrote of “zones” or “horizons” as being distin uished by the constant and exclusive occurrence of certain species. Therefore the zone is defined by the range or vertical distribution of species (or better an assemblage of organic remains), irrespective of stratal or lithological incidentals. Sub-zones consequently are smaller divisions of geological time, characterized by the local restriction of certain index species. The value of these local subzones for purposes of an ideal time-scale (Oppel's “ideales Profil”), in my opinion, is nil. If the Champfromier sequence had been worked out before that at Charmouth, the order of Upper Sinemurian “hemerae” (rashly adopted in some textbooks) would have been very different. It is clear that the restricted occurrence of any particular ammonite at a given locality is something entirely different from the actual date of existence (range or hemera) of this species.