This mildew was collected on two types of Rubus australis Forst. on the leaves only of the broad-leaved type, but on the leaves, twigs, and buds of the narrow-leaved. Conidia only were found on the twigs and buds, while on the leaves of both forms both old conidia and perithecia were present. The perithecia, however, were mature, only on the broad-leaved specimens at the time of collection.

The mycelium forms white felty patches irregular in shape and size, which in time tend to become dense, but may be sparse and powdery when young or where less developed; chiefly hypophyllous, rarely epiphyllous also; consisting of superficial, dense, branching and intertwined hyaline hyphae, 3-5 mmm. thick. (Figs. 14, 15).

The perithecia are numerous, scattered, hypopyllous, superficial, ,golden brown, becoming dark brown, spherical, 90-140 (most .100-120) mmm. in diameter; the wall consists of two or three layers of thick-walled selerenchymatous cells on the outside merging gradually into the thin-walled cells surrounding the asci (Fig. 1) ; attached to the, perithecia are appendages which are sparse or numerous, intermixed with and difficult to distinguish from the hyphae of the mycelium, straight to much contorted or knotted, occasionally slightly branched, hyaline or very rarely faintly fuliginous, 25-100 mmm. long or exceptionally up to 1.5 times the width of the perithecium (usually equal to one half to the whole diameter of perithecium), 3-5 mmm thick. (Figs. 2 & 3).

There are 4-17 asci in each perithecium; paraphyses are absent; asci 8-spored, saccate to ovate-oblong, often irregular in shape, 58-82 mmm. long by 28-36 mmm. wide, with a short broad stalk 8-13 x 5-6.6 mmm.; wall of ascus 1.7 mmm. wide. (Fig. 4.)

The ascospores are continuous, hyaline, almost spherical to broadly elliptical, 13-21.5 x 10-12.4 mmm., with granular contents. (Fig. 5.)

The conidia are continuous, hyaline, rounded, or oblong-elliptical to oblong-cylindrical with bluntly rounded ends, ranging from 28-40 mmm. long by 13-18 mmm. wide. (Fig. 6.)

Five species of Erysiphe are recorded for New Zealand, but in the major features of number, shape and size of asci and ascospores the fungus on Rubus agrees only with E. carpophila Syd. (Sydow,. 1924, p. 294) on Weinmannia sylvicola Sol.

In the latter fungus, however, the perithecia.a are somewhat larger and their appendages longer. Moreover, in the single set of material from which the description of E. carpophila was drawn up, it occurred on the capsules only, the leaves being uninfected. But in view both of the agreement of the fungi in their more important characteristics and also of the wide range of hosts upon which the common species of Erysiphe are found, it seems advisable at present. considering our ignorance of the distribution of Erysiphe on native plants, to record the form on Rubus as a form of E. carpophila rather than to assign it immediately to a new species. The new form is therefore designated E. carpophila Syd. var. rubicola.