Perithecia black, scattered or more often gregarious (occasionally two perithecia may be found with the beaks united), sunken in the bark, which when wet may be stripped off the wood, carrying with it the globose Perithecia, the round, shining black bases of which are then exposed, the bases contracting inwards when drying (Plate 11, fig. 4) ; beak straight or bent, 100-390 mmm. long X 230-330 mmm. broad, narrowed above, perforating the periderm and raising the epidermis to form a little round pustule through which the tip of the beak projects (text-fig. 5), thickened, and swollen flask-shaped below, consisting of small blackish compressed angular cells which are smaller and arranged in parallel-fibred structure bordering the central canal, which is usually bent spirally or may be straight ; wall of the perithecia of two layers, the outer consisting of several rows of blackish angular thick-walled cells, the inner of several rows of thin-walled hyaline parenchymatous cells which are often compressed laterally (text-fig. 6). Asci 70-100 x 12-17 (most 14-16) mmm., clavate, narrowed at the apex, sharply attenuate below, having in the young ascus a long filiform stalk which in the mature stage breaks off or becomes swollen and shortened though usually still basally attenuate; wall of ascus very thin, except at the apex, where it is thickened and opens by a pore, 8-spored, distichous ; paraphyses absent (text-fig. 7). Spores oblong-elliptical, some obtusely rounded at both ends, others somewhat rounded-fusoid, straight, more often unequal-sided or slightly curved, uniseptate, slightly constricted by the septum which is at or near the centre, hyaline, 16-23 x 5-7 mmm., contents granular or guttulate.

Throughout the district this is one of the commonest saprophytes occurring upon dead twigs and branches still attached to the trees, particularly on those twigs which have died the season before. It occurs more frequently and abundantly upon the weeping-willow than on the crack-willow.M

Species.-The species differs markedly from Gnomonia pleurostyla Auersw., the one species of Gnomonia recorded by Saccardo (Syll. Fung., vol. 1, p. 569) for the willow. G. pleurostyla is found on dead leaves; the asci are six-spored, the spores filiform lance-shaped, 50-55 x 2 mmm. Winter, in Rabenhorst's Krypt. Fl. (1887, p. 589), gave G. apiculata (Wally.) Wint. on the willow, but expressed a doubt as to whether the species really belonged to this genus ; and later Petrak (1921, p. 176) showed that it was identical with a species of Cryptodiaporthe on Populus, and that it should therefore be called Cryptodiaporthe apiculata (Wally.) Petr. Petrak (1921, p. 180) has also transferred G. salicella (Fr.) Shroet. to Cryptodiaporthe salicella (Fr.) Petr. E. M. Doidge (1924, p. 56) records Gnomonia sp. upon Salix sp. in South Africa, but gives no diagnosis and does not state the species. Moesz (1918, p. 60) describes G. salicina n. sp. upon dead branches of Salix albs. Unfortunately, this paper is not available. These are the only records of species of Gnomonia found upon Salix, and a comparison with the other species of Gnomonia found on different hosts shows that the species found here does not agree entirely with any of them, and in the absence of Moesz' paper it seems justifiable to separate it as a new species.

Relationship to other Fungi.-As this fungus so frequently occurs on dead still-attached twigs which were infected with Marssonina the season before, the question arises whether this may be the ascigerous stage of the fungus of which Marssonina is the conidial stage. This is not unlikely, as Klebahn (1905, p. 336) has demonstrated by cultures and ascospore infection the connection between Gnomonia leptostyla and Marssonina juglandis (on the bitter-nut Juglans cinerea). On the other hand, other species of Gnomonia have been shown to have different conidial forms, chiefly Gloeosporium, Asteroma, and Leptothyrium. Of these genera, Gloeosporium capreae has been found on Nelson willows. According to Klebahn (1918, p. 317), the conidial forms of Gnomonia belong to the Melanconiaceae, so either Marssonina salicicola or Gloeosporium capreae may prove to be the conidial form of Gnomonia bullata. The fungus germinates very readily in water (four hours), (text-fig. 8), in nutrient agar (turnip, willow, &c.), and in a solution of soluble substances from the willow. Healthy cultures of vegetative growth were readily obtained and watched to see if conidial stages would be produced, with a view to proving whether or not this Gnomonia were connected with the Marssonina so common on the same trees, or with the Gloeosporium common on Salix fragilis. So far none of the cultures have produced spores. It is also intended to undertake inoculation experiments to see if one of the parasitic diseases may be produced by this common saprophyte. Petrak (1921, pp. 176, 1.80) has proved that several recognized species of Gnomonia belong to the genus Cryptodiaporthe, and the question arises whether the one under consideration may also belong to the latter genus, as in some cases two perithecia were found with their beaks partially or completely joined and having a common mouth, and there is always a marked thickening round the beak, which suggests the possibility of a rudimentary stroma, of which, however, there is no other sign. A great quantity of material has been available, and careful examination has not furnished any evidence in favour of this view. Except in the instances mentioned, perithecia were separate, although crowded ; the type of perithecium. and the structure of the ascus have the marked characteristics of Gnomonia, in which genus the fungus has been placed.