In 1838, the Rev. M. J. Berkeley announced the discovery by him of a singular production, for which he was unable to find a fitting location in any genus then established, and for which he accordingly characterized a new one, under the name of _Ascotricha_. This new species of paper mildew was found by him on some printed paper in a box. It somewhat resembles the other species above alluded to, at a casual glance; but more minute examination will reveal its differences. The author to whom we are indebted for this species thus describes its development. At first it appears as a minute branched mould interspersed with globose brownish conidia. As it advances in growth, globose black peridia become visible amongst the threads, clothed with and supported by alternately branched obscurely-jointed filaments, the branches of which generally form an acute angle with the stem (fig. 254). The ramification of these is very peculiar, the stem and main shaft of each sub-division being almost constantly shortened and surmounted by the branches given off near its apex; this, again, is often abbreviated and another branchlet given off, which again surpasses it; and occasionally the same circumstance takes place a third time. The apices are clavate and colourless; the rest of the filaments, when viewed by transmitted light, brown, even, and pellucid: a few globose conidia are usually attached to them (fig. 255). The conceptacle is thin, black to the naked eye, of an olive-brown under the microscope, filled with a mass of linear extremely transparent asci (fig. 256), each containing a single row of broadly elliptic chocolate sporidia. These have a paler border; sometimes the colour entirely vanishes, either from age or abortion, and there is only a minute globose nucleus or more probably a vesicle of air, in the centre; occasionally they become so transparent that the globular bodies alone are visible. After the conceptacles burst, several are frequently collected together into an irregular linear body, which consists principally of the conglomerated sporidia. One other very common and troublesome little fungus (_Eurotium herbariorum_) will for the present close our examples. This is found creeping over dried plants preserved in herbaria, on decaying fruit, preserves, and various other substances, sometimes animal as well as vegetable, but chiefly the latter. To the naked eye it appears as a myriad of little yellow spherical bodies, of the size of very small pins’ heads, resting upon fine cobweb-like threads (fig. 260). When magnified, the surface of the conceptacles is seen to be reticulated (fig. 261). In the interior the sporidia are borne, contained also, as in the former instance, in asci. It has been considered _probable_, but as yet not fully proved, that this mildew is a compound fruited (ascigerous) condition of an equally common mould (_Aspergillus_).