_The Tubes._—Funguses of the genus _Boletus_, etc., present on their under surface, in place of gills, series of small hollow cylinders or tubes; which are for the most part soldered side to side like the cells of a honeycomb, but in the _Fistulina_ are unconnected. Like the gills, they are prolongations of the fibres of the pileus, but lined, instead of coated, by the hymenium; their free extremities are the pores, which at first are closed, but afterwards open to let the seed escape: they are generally of equal length and simple, but sometimes in the interior of a large one smaller tubes may be discerned, in which case the first is termed compound. With reference to the stalk, they are either adnate or decurrent, they first appear as a network formed by slight prominences of the fibres of the pileus; if at this early period a portion be removed together with a piece of the flesh, it is reproduced in a few days and the tubes developed as usual. The beautiful reticulations observed on the stalk of some Boletuses are produced by abortive tubes decurrent along their surface. _The Plaits_: Venæ, Plicæ.—The plaits of the Chanterelle are formed like the gills and tubes of the mushroom and Boletus, _i. e._ by the fibres of the flesh running down from the pileus, and invested in a reduplication of the hymenium; with this difference, however, that while in the two latter the seed membrane is divided into as many portions as there are gills or tubes, in the former the continuity of its surface is perfectly unbroken. These plaits (_plicæ_) are always late in appearing, and sometimes are only developed when the fungus is about to cast its seed. _The Spines_: Aculei, etc.—The under surface of the pileus in the genus _Hydnum_ is shagged with vegetable spines or teeth (_dentes_, _aculei_) of unequal lengths, generally isolated, but sometimes connected at the base, and formed originally out of a congeries of minute papillæ invested by the hymenium, which gradually elongate their fibres and assume this form. Light seems essential to their production, for if a Hydnum grow in the dark, the teeth shrink up into long threads and are sterile. METHODICAL DISTRIBUTION OF THE BRITISH ESCULENT FUNGUSES. The primary division of Funguses into _Hymenomycetes_ and _Gasteromycetes_ is founded upon the position of their seed, which lies, as we have seen, externally in the first, and internally in the members of the second. The funguses described in the present work belong chiefly to the first division, _Hymenomycetes_; to Tribe 1, _Pileati_; and many of them to Genus 1, _Agaricus_. This genus includes a great variety of species, and is distinguished from all other genera by having a fleshy pileus furnished underneath with _gills_, which are placed at right angles to the stem. Some species, during their infancy, are enclosed either in one or more membranes. DIVISION I. HYMENOMYCETES. TRIBE 1. _PILEATI._ GENUS 1. AGARICUS.