Habitat: Parasitic upon the spermogones, aecidia, uredosori, and teleutosori of numerous Uredinales; saprophytic upon the leaves of deciduous plants. Distribution: Europe; North and South America; Africa; Ceylon; Japan; Australia. Although eight species have been described, only one has been collected here. It is probable that many of these so-called species are but variable forms of D. Filum, as in many instances they appear to have been erected on slight differences in the size of the spores, a character too variable to be considered specific; for, as is shown below, in D. Filum alone the spores on different hosts range in length from 10 to 18 mmm.; furthermore, this variation may be seen in the spores from a single pycnidium. 1. Darluca Filum Castagne. (Text-fig. 126, and Plate 2 fig. 5.)  Uredinales. Cast., l.c. Sphaeria Filum Biv.-Bern., Bernh. Stirp. rar Sic. Manip., vol. 3, p. 12, 1815. Phoma Filum Fr., Syst. Myc., vol. 2, p. 547, 1823. Pycnidia superficial or immersed, scattered or gregarious, conicoglobose, elliptical, obovate, or depressed-globose, 90–120 × 60–100 mmm. diam., ostiolate, smooth, black. Conidia 1-septate, hyaline, fusoid, smooth, 10–18 × 3–6 mmm., slightly or not constricted at the septum, muticate. Habitat: Parasitic upon the spores of the following species: Uromyces otakou G. H. Cunn. (II); U. Polygoni Fcl. (II); Uromycladium alpinum McAlp. (II); Urom. notabile McAlp. (II); Urom. Tepperianum (Sacc.) McAlp. (III); Puccinia Caricis Schroet. (II, III); P. Chrysanthemi Roze (II); P. Coprosmae Cke. (III); P. Elymi Westnd. (II); P. Hoheriae Wakef. (III); P. Hydrocotyles Cke. (II); P. juncophila Cke. et Mass. (II); P. Morrisoni McAlp. (II); P. Plagianthi McAlp. (III); P. Poarum Niels. (II); P. pulverulenta Grev. (II); P. punctata Link. (II); P. whakatipu G. H. Cunn. (II); P. Unciniarum Diet. et Neg. (II, III); Phragmidium novae-zelandiae G. H. Cunn. (I); Phr. Potentillae P. Karst. (I, II); Fig. 1.—Phragmidium Acaenae G. H. Cunn. Caeomata and teleutosori from Acaena microphylla Hook. f. Arrows point to the minute teleutosori. Fig. 2.—Phragmidium norae-zelandiae G. H. Conn. Teleutosori from Acaena novae-zelandiae T. Kirk. Fig. 3.—Phragmidium Potentillae P. Karst. Teleutosori on Acaena Sanguisorbae Vahl. Fig. 4.—Hamaspora acutissima Syd. Teleutosori on Rubus australis Forst. f. Note the long and much-entwined fibrils. Arrow points to sori from which the fibrils have disappeared. Fig. 5.—Milesina Histiopteridis G. H. Cunn. Uredosori on Histiopteris incisa (Thunb.) J. Sm. The white spots consist of numerous uredospores which have exuded from the immersed peridia. Fig. 6.—Melampsora Lini Desmaz. Teleutosori on Linum monogynum Forst. Fig. 7.—Aecidium Milleri G. H. Cunn. on Aristotelia serrata (Forst.) Oliver. Fig. 8.—Aecidium Ranunculacearum DC. on Ranunculus Lyallii Hook. f. Fig. 9.—Aecidium hupiro G. H. Cunn. on Coprosma foetidissima Forst. Fig. 10.—Aecidium kowhai G. H. Cunn. on Edwardsia tetraptera (J. Mill.) Oliver. Photo by E. Bruce Levy. Fig. 11.—Aecidium Myopori G. H. Cunn. on Myoporum laetum Forst. f. Natural size. All photographs, with the exception of fig. 10, by the writer.