Key Based on Gall Characters 1.Gall of globose type 2 Gall of longitudinal type 3 2.Height greater than diameter, spines short, few, on dome-shaped projections C. nigra Height less than diameter, spines long, numerous, not on projections C. gunnii 3.On N. menziesii C. pallida On N. moorei C. septentrionalis From the information available, the genus can be divided into the following two groups:—Species with pycnidia are marked (p) and the most primitive are placed first. Group 1. Longitudinal Galls 1.C. hookeri (p). 2.C. berteroi. 3.C. pallida. 4.(?) C. septentrionalis (p?) Group 2. Globose Galls 5.C. darwinii (p). 6.(?) C. johoii (p) (galls not described). 7.C. nigra (p?). 8.C. espinosae. 9.C. harioti. 10.C. gunnii. 2.The stroma or fructification The stroma is compound and is apparently formed through the fusion of numbers of simple stromata each bearing one apothecium. The stromata arise from the spines produced in the wood of the host by the action of the parasite. These spines, consisting of fungal hyphae and woody tissue, project from the hypertrophied woody growths and extend through the bark nearly to the exterior. As the stroma enlarges it assumes a more or less spherical form with an oval apical portion and conical basal portion, it is jelly-like or rubbery in consistency and is covered by a tough skin or cortical layer. Apothecia are formed beneath this layer, which becomes tightly stretched and ruptures at maturity. The medulla or central portion of the stroma is a mass of hyphae through which cartilaginous fibres run from the point of attachment and ramify towards the cortex. The main features in the structure of the stroma, many of which are useful for purposes of identification, are as follows:— (a) The External Cortical Layer. The stroma is covered by a tough elastic skin or pseudoperidium which may be dry (as in C. gunnii) or hygroscopic, (as in C. pallida) or covered with black incrustations of carbonaceous material (as in C. nigra and C. septentrionalis). It may be perforated, between the apothecia by openings raised on various types of papillae. At maturity the cortex covering the mouths of the apothecia becomes membranous, tightly stretched, and finally ruptures, rolling back in a characteristic manner. The cortex of the basal portion of the stroma is usually striated, fluted or flattened, but not perforated by apothecia. (b) The Apothecia. The hymenial layer arises in hollows which form within the stroma beneath the cortex, and between the papillae and internal fibres in species in which these occur. During their formation the apothecia are filled with a very clear, highly refractive, mucilaginous substance which disappears some time before the spores are ripe. The hymenium consists of asci and paraphyses arising from a sub-hymenial layer of