Obs.—As distinguished from Serpulites, the term Serpula is here made to include those tubes which were attached, or in all probability attached by some portion of their surface to other objects, and in which there is an absence of the thickened margins, and the posterior bifurcating shelly tubes of the former. The name can only be used in an approximate sense, for it is quite within the bounds of possibility that any of the species here referred to Serpula may be shown to have other affinities. Already two out of the limited number of British Carboniferous species have been so indicated. The fine rigid siliceous rods formerly called Serpula parallela, M'Coy, are now known to be the anchoring fibres of a sponge allied to Hijalonema, whilst it is more than probable that Serpula hexicarinata, M'Coy, is the corallum of a species of Heterophyllia.

The association of stibnite and cinnabar appears to have been first noticed at El Haminat, in the province of Constantine Algiers, where, during the years 1850 to 1852, considerable quantities of both these minerals have been raised from veins traversing Cretaceous schists. Other localities in Algiers showing the same association are: Ghelma near Phillipsville, where cinnabar in crystalline crusts covers and penetrates antimony ochre derived from the decomposition of stibnite, the containing rock being a saccharoidal limestone; Debar, 19 kilometers to the N.W. of Ghelma, where stibnite is found covered with spots of cinnabar, the gangue being heavy spar; Traia, showing a similar occurrence to the preceding; Tasselemet, where radiating crystals of stibnite occur imbedded in earthy cinnabar.