HARD WICKE'S S CIENCE- G O SSI P. 



77 



asci, which contains them, are barren or empty asci, 

 called paraphyses. * The cups are of a brownish 

 colour, not unlike very thin gutta percha, brittle, the 

 hymenium soft and velvety from the compact layer of 

 asci with which it is covered. Xylaria hypoxylon has 

 the habit of Clavaria ; it is black, greyish at the 

 summit, hairy below. The horny receptacles in which 

 the asci are contained are called perithecia. 



Sphaeria is something of a lichen in its habit of 

 growth. The genus has been of late years split into 

 several sub-genera : the distinctions are difficult to 



Sapedonium, yellow boletus mould as it is called ; an 

 agency by which one fungus is converted into a mass 

 of spores produced by another ; frequent : and Tuber- 

 cularia (fam. Stilbacei), little excrescences on dead 

 wood ; they are composed of compacted threads ; also 

 frequent. In conclusion we would refer those of our 

 readers who may be interested in microscopic mycology 

 to the splendid work of the brothers Tulasne on the 

 subject, in which the growth of the reproductive 

 agency from the tissue, and various forms it assumes 

 are most admirably figured and described, while 



Fig. 71. — Peziza vesiculai'is. 



Fig. 72. — Xylaria 

 hypoxylon. 



Fig. 70. — Vertical section of rhallns impudkus, 

 in the young state, showing the hymenium, 

 gelatinous intermediate layer, and undeveloped Fig. 73 

 stipe. 



make out ; we refrain therefore from naming our 

 specimens, and confine ourselves to remarking that 

 they are black excrescences usually found on the bark 

 of dead branches of trees, with carbonaceous perithecia, 

 pierced at the apex and mostly papillate. The higher 

 forms of these Ascomycetous fungi are represented by 

 the truffle and morel. The types of other families 

 belonging to the'order are Hypoxylon and Phacidium. 

 Specimens of Phacidium we found upon the leaves of 

 a sycamore tree at Woodford. We would also observe 

 that the "perithecia " of the Ascomycetes proper must 

 not be confounded with the " sporangia " of a section 

 of moulds which comprise the family of the Physco- 

 mycetes associated with them. These growths are 

 forms which should occupy a position intermediate 

 with the Hymenomycetes : the contents of these 

 " sporangia " are simple spores, not sporidia. Of the 

 rust, smut, mildew, mould (not physcomycetous) and 

 other microscopic growths found upon vegetable 

 matter of different kinds which compose the Conio- 

 mycetous and Hyphomycetous orders, we have also 

 two curious growths belonging to the latter, viz., 



-Asci of Peziza vesicularis ; b, sporidia : 

 all magnified. 



Epping Forest, well explored, 

 will afford abundant material 

 for study. 



P.S. — At page 254, No. 167, 

 errahcm. Pleiirotus : add, " 

 lateral or excentric." 



t 



Fig. 74. — Xylaria hypoxy- 

 lon; b vertical section 

 showing the perithecia ; 

 c an ascus of the same 

 containing sporidia. 



Stem, when present, 



* Besides these, simple cells, called gonidia, attached to simple 

 filaments, have been observed in these as in most kinds of fungi. 



Note. — Pholiota aureus: said not to be the true 

 species known by this name and very rare, but an 

 allied form, P. spectabilis. 



{Concluded.) 



LIMESTONE AS AN INDEX OF GEO- 

 LOGICAL TIME. 



THIS is the title of a paper recently read before 

 the Royal Society, by Mr. T. Mellard Reade, 

 C.E., F.G.S. The author showed that the geo- 

 logical history of the globe is written only in it-- 

 sedimentary strata, but if we trace its history back- 

 wards, unless we assume absolute uniformity, wes 

 arrive at a time when the first sediments resulted 

 from the degradation of the original crust of the 

 idobe. There is no known rock to which a geologist 



