"When the printing of the species of this, the 2nd Part of the Class _Cryptogamia_, was commenced, I thought myself highly fortunate to have obtained the assistance of my valued friend, the _Rev. M. J. Berkeley_, in preparing the first Tribe, _Pileati_. I have now to express my cordial acknowledgements (in which I am satisfied I shall be joined by every Botanist in the country) to that gentleman for having kindly undertaken to prepare the whole of this vast family for the press: and it is certain that the task could not have fallen into better hands." The volume contains detailed descriptions of all British fungi known at the time, amounting to 1360 species, included in 155 genera, the great majority of which had been studied by the author in a living condition, and also compared with specimens contained in various exsiccatæ and with the very extensive collection owned by Sir W. J. Hooker. The appearance of this book at once placed Berkeley in the front rank of Mycologists, and it was universally admitted as the most complete Mycologic Flora of any country extant; and furthermore, so far as accurate information, and a true sense of the conception of species are concerned, the same statement holds good at the present day. At this date our knowledge of extra-European fungi was almost nil, with the exception of a few woody cosmopolitan species collected by various travellers, more as matters of curiosity than for the advancement of our knowledge of the fungus-flora of the world.