A N ALIEN SPECIES: XYLOBOTRYUM CAESPITOSUM A. Lm SM.

By A. Lorrain Smith, F.L.S.

Among the specimens acquired by the Trustees of the British Museum from the late Mr. W. Phillips, there is one which was described and figured by him in the " Gardeners' Chronicle," August 7, 1875, as a new lichen species under the name Sphinctrina caespitosa. The diagnosis given by Phillips runs thus : -

Apothecia globose, subglobose or deformed, stipitate, densely caespitose, stipes (from a to 14 line long) horny, often branched ; sporidia oblong, rounded at the ends, uniseptate, fuscous, .ooo5 x ,0001 5 i i

On decayed fungus, probably PoZyporzts, Hereford, Mr. Griffith Morris.

'l'he figurcs are rcpruducecl fro111 Phillips' original drawings. .r, I'lant nat . size. B , A group of specimens magnified. c , Section of an entire plant, seen by transmitted light, magnified. u, Section of the apothecium, more highly magnified. E, Spores very highly magnified.

The specimens are well preserved ; the apothecia are densely caespitose, the bases of the stalks penetrating the fungal sub- stratum and then being welded together. They measure about 3 to 4 mm. in height, and are fairly stout ; the heads, slightly wider than the stalks, are irregularly globose and measure about + mm. across. The paraphyses are numerous and stoutish, but their outline is mostly lost, as they are mucilaginous and co- herent. The asci are also indistinct, they are long and narrow, measuring about 6p in width. The spores are uniseriate, or partly biseriate, in the ascus, brown, I-septate, 6-8p x 3p. The form of the upright stroma, the globose perithecia and the brown spores indicate the position of the plant in the fungus genus XyZobotryum, one of the Xylariae.

The genus XyZobotryztm includes very few species collected in tropical regions on rotten wood. It seems to me that the specimens collected at Hereford are due to some accidental in- fection, and that the fungus has been unable to survive in our cold climate. It is so well-marked, it could not otherwise have escaped being collected once and again.

As described by Phillips it "forms a dense layer covering several inches ; the stem is black, shining, and of a horny tex- ture, frequently branched ; the head in aged specimens becomes dusty from the breaking up of the hymenium."

The lichen family, Caliciaceae, to which Sfhinctrina belongs, is characterized by the formation of " mazaedium " fruits, in which the spores become free as they mature, by the breaking down of the asci and remain massed on the disc of the apothecia. The species of Sphinctrina are sessile and are usually parasitic on other lichens. The Hereford specimen is not sessile nor is it parasitic on another lichen, and there is no trace of a lichen thallus. The head may be somewhat dusty in old specimens but there is no trace of a " mazaedium." The plant is undoubt- edly a fungus belonging to the genus XyZobotryum.