The fungus consists of a volva and a globose to ovate receptaculum. When mature the receptaculum partially emerges from the enclosing volva, but its lower half remains loosely held within the latter by the lobes into which it has split (Pl. XV, Fig. 1). In the largest specimen found, in which the receptaculum was in its final position, the length from the free end of the receptaculum to the base of the volva was 22 in., while the width of the receptaculum was 2 in. The volva is ovate before rupture, fleshy-firm in texture, and when undisturbed in the soil is white, but on exposure to the air becomes a reddish brown. When mature it ruptures into usually five pointed segments whose length is 1/3 to 1/2 that of the whole volva. The segments do not become reflexed, but tend to lie in the position they occupied before cleavage, with the result that they rest lightly upon the receptaculum from its equatorial region downwards, and so prevent it from emerging completely. The volva is composed of two layers, the outer of which is a firm, thin, finally coloured pellicle, while the inner is a wider, gelatinous, white layer, slippery to the touch, and thin above where the segments are formed, but gradually increasing in thickness in the equatorial and basal regions, where a width of 1-5 to 2 mm. is attained (P1. XV, Fig. 2). The volva narrows at the extreme base and through it at this point there passes up from the exterior a slender, fibrous strand about 2-5 mm. wide and 7 mm. high. The upper end of this strand is attached to the base of the receptaculum and the lower end is doubtless continued into a rhizomorph, although this was not secured with the specimens. As the receptaculum enlarges at maturity and is forced up the volva by the swelling of the gelatinous inner layer of the latter, it breaks away from this strand and thenceforth has a small hole at its base where the strand was originally attached. The strand, though small, remains visible even in old specimens and can be seen transversing and projecting a few millimetres within the gelatinous layer of the volva.
The receptaculum is simply a smooth white shell with a large central cavity. As already mentioned, it may be z in. across, and as the wall is only from 5 to 8 mm. thick, the diameter of the central cavity is rela tively enormous. The structure of the wall is noteworthy. It consists entirely of meshwork, the strands of which are delicate except where several join, and the rounded cavities of which, though ranging in size, are usually large, often attaining a diameter of more than a millimeter (Text-fig. 4).
The hymenium is arranged in a layer of small chambers extending over the inner surface of the receptaculum, and therefore in contact with the cavity of the interior. When mature the walls of the hymenial chambers rupture, and the spores and the disintegrating hymenial and subhymenial tissues together form an intermittent and at times jagged layer over the inner surface of the receptaculum (Text-fig. 4).
MORPHOLOGY.
Volva. The outer surface of the pellicle consists of a dense aggregation of hyphae which in the unexposed volva when buried in the soil are hyaline, but which become a light brown, when viewed in section, when the volva has been exposed to the air. These hyphae are sparingly septate and branch infrequently at a wide angle. The width of the branch-hyphae is almost equal to that of the parent hyphae from which they arise. They are about 2 µ wide and the greater part of this width is occupied by the lumen. The free ends of the hyphae are sometimes irregularly upturned, causing a minute roughness on the surface of the volva. Such colour as is present is confined to the hyphae at the surface, those below being hyaline. The sub-epidermal hyphae, although belonging to the pellicle, exhibit transitional stages not only in loss of colour but in the change from the parallel arrangement characteristic of the surface layers to the loose weft which occurs throughout the inner gelatinous layer. In addition, branching becomes less frequent in the inner part of the pellicle, and the width of the hyphae is reduced, until finally it is no greater than that of the extremely slender hyphae characteristic of the gelatinous layer. In the latter region they are rarely branched and are distributed throughout the gelatinous matrix seemingly indiscriminately as far as direction is concerned; but evenly and sparsely with regard to one another (Text-fig. 3). There is no differentiation into a membrane on the inner surface of the volva, matrix and hyphae merely ending abruptly in a smooth, slippery surface, the hyphae of which show no closer aggregation than is to be found deeper in the layer.
Receptaculum. The wall of the receptaculum is usually three to four chambers wide, but if the latter are small they are correspondingly more numerous (Text-fig. 4). The outline of the chambers is spherical, oval, or even angular, but with the angles rounded, never sharp. The mesh of the wall consists of extremely thin-walled, usually spherical cells which are peculiarly uniform in size. The strand at its narrowest part, i. e. where it lies between two cavities, is three cells wide as a rule, but it is not unusual for there to be only two cells, and on rare occasions single-celled strands have been observed. At the junction of several strands, on the other hand, the number of cells is increased and may be as many as twenty (Text-fig. 5). No thickening of the cell-walls, nor closer aggregation, occurs at either surface of the receptaculum, all cells alike, from one surface to the other, being characterized by extreme delicacy, uniformity of size, and high water-content.
The hymenial cavities are more or less lenticular in shape and are arranged edge to edge with their longer axis in the plane of the surface of the receptaculum (Text-fig. 4). There is at times only a single row of sterile cells separating the hymenial chambers, but the width of this intervening tissue is not uniform and it may even exceed that of the chambers. The width of the chambers varies from 100 to 250 µ, while the height is not usually greater than 100 µ.. Even the smallest chambers seldom contain less than 100 spores and in the larger the number is nearer 1,000. The spores are borne over the whole surface of the chamber-on the inner surface of the covering wall as well as on the surface adjoining the receptaculum. Fragments of the wall covering the chambers were secured, and sections and surface views of them obtained (Text-fig. 5). The cells of these walls are angulled rather than rounded, and smaller than those of the receptaculum generally. The wall in this part seems not to have been more than three cells wide and in some instances was only that of a single cell (i. e. in addition to the hymenium and subhymenium).
All the specimens obtained were mature, and basidia were no longer to be found. Moreover, internal decay sets in early in these fruit-bodies, and the structure of even the subhymenium could not be followed in any of the specimens. The conjugate nature of the nuclei, however, is still evident even in cells which have collapsed. The spores are brown in the mass but yellow with a slight fuliginous tone in transmitted light. In shape they are elliptical to rounded-elliptical, and are either symmetrical or have one side less curved than the other. As a rule, however, they are symmetrical and vary in size from 8 µ to 13 µ, x 5 µ. to 6 µ. (Text-fig. 6). Both ends are rounded, but the free end may be slightly narrower than the base. The wall is smooth and the contents are clear, while the protoplasm is slight and the vacuoles relatively large. The spore is binucleate, the two nuclei lying as a rule side by side in. a small cytoplasmic aggregation suspended in the centre of the spore by extremely delicate strands. It frequently happens that both nuclei lie in the plane of the longer axis of the spore, but this is not invariable. The only remarkable feature that the spores exhibit is the presence at their lower end of a persistent, stout, hyaline, obconic papilla (sterigma). This papilla is about 1.5 µlong and 0.75 µ wide at its widest part, which is at its point of attachment to the spore.

The specimens were growing at a height of 1,500 ft. above sea-level, near the edge of a path, among moss and practically under tea tree (Leptospermum scoparium, Forst.).

[English diagnosis]
Claustula Fischeri, gen. et sp. nov. Volva ovate, about 14 in. in diameter, at first white, then reddish brown, outer layer thin, coloured, inner layer wide, gelatinous, white; splitting above into usually five pointed lobes.
Receptaculum globose, white, smooth, up to 2 in. long, permanently closed, originally attached at base by fine strand to volva, ejected at maturity but held by lobes of volva; wall of receptaculum three-four chambers wide, mesh between chambers usually three cells wide, but may be twenty at the angles; cells thin-walled, more or less spherical, uniform in size, forming a pseudoparenchyma ; hymenial chambers about 200 µ, x 100 µ in a single layer over the inner surface of receptaculum ; spores brown in mass, fuliginous-yellow in transmitted light, elliptical, smooth, 8 µ to 13µ x 5 µ to 6 µ, with basal papilla 1.5 µ x 0.75 µ.

The fungus is either an unusual member of the Phallineae or has affinities with that group. In the absence of material sufficiently young to trace its early development, its systematic position cannot be fully determined It shows greatest resemblances in form to those members of the genus Clathrus, segregated by Lloyd as Laternea, in which the divisions of the receptaculum are few in number and united at their apex. But so far there is no recorded case in which a species of Clathrus has failed to exhibit any divisions. Moreover, the cellular structure of the receptaculum of Claustula resembles that of the stalk of certain species of Simblum, Anthurus, Colus, Aseroi, and Phallus, in which the cells form a pseudoparenchyma, rather than that of the receptaculum of Clathrus, where the cells on the whole are tubular. If one could conceive a Simblum or a Colus, or even an Aseroe, in which the gleba is located within the hollow stem instead of at the top of it, and developed generally over the interior instead of being confined to definite areas, and which, moreover, either has not yet evolved or possibly has lost the power of developing any of the various methods of exposing the spores characteristic of these genera; then the organism so conceived would not be unlike that at present under discussion. Both Anthurus and Colus include species, with few arms in the receptaculum, in which variation in the number of the arms is common. A form lacking arms would therefore not greatly differ from some of the simpler types of these genera already known.
Again, the genus Sphaerobolus exhibits some resemblance to the present genus. The receptaculum is more complex, being composed of three layers instead of one as in Claustula, but of these three layers the outer and part at least of the inner are similar in their pseudoparenchymatous nature to the receptaculum of Claustula. The gleba of Sphaerobolus, on the other hand, fills the space within the receptaculum instead of lining its inner surface.. Nevertheless, there is a certain resemblance in the grosser features of the two genera. The spores, moreover, are more clearly of the shape and size of those of Sphaerobolus than of the small spores characteristic of the Phallineae. A further characteristic in which Claustula differs from members of the Phallineae is in the absence of gluten from the spores, for in the present genus they are only slightly viscid to the touch.
In the absence of details of the early development of Claustula speculation as to its relationships with other genera must necessarily be hazardous, and it is therefore hoped that early stages will be found, so that its systematic position may be established.

DIAGNOSIS. Claustula, gen. nov. Volva ovate, up to 2 in. in diameter, white at first, finally coloured, of two layers, outer thin, inner gelatinous, rupturing above at maturity into several pointed segments; receptaculum globose, permanently closed, partly ejected from volva at maturity, with large central cavity and wall of meshwork; gleba in small chambers on inner surface of receptaculum ; spores brown, smooth, cylindrical with persistent basal papilla.

[see Claustula fischeri]