CLASSIFICATION. 77 



examined more in detail. The Tuleracei, OP subterranean 

 Ascomycetes, are analogous to the Hypogcsi of the G aster omycetes. 

 The truffle is a familiar and highly prized example. There is a 

 kind of outer peridium, and the interior consists of a fleshy 

 bymenium, more or less convoluted, sometimes sinuous and con- 

 fluent, so as to leave only minute elongated and irregular cavi- 

 ties, and sometimes none at all, the two opposing faces of the 

 hymenium meeting and coalescing.* Certain privileged cells 

 of the hymenium swell, and ultimately become asci, enclosing a 

 definite number of sporidia. The sporidia in many cases are 

 large, reticulated, echinulate or verrucose, and mostly somewhat 

 globose. In the genus Elaphomyces, the asci are more than 

 commonly diffluent. 



The Elvellacei are fleshy in substance, or somewhat waxy, 

 sometimes tremelloid. There is no peridium, but the hymenium 

 is always exposed. There is a great variety of forms, some 

 being pileate, and others cap-shaped, as there is also a great 

 variation in size, from the minute Peziza, small as a grain of 

 sand, to the large Helvella gigas^ which equals in dimen- 

 sions the head of a child. In the pileate forms, the stroma 

 is fleshy and highly developed ; in the cup-shaped, it is 

 reduced to the external cells of the cup which enclose the 

 hymenium. The hymenium itself consists of elongated fertile 

 cells, or asci, mixed with linear thread-like barren cells, called 

 paraphyses, which are regarded by some authors as barren asci. 

 These are placed side by side in juxtaposition with the apex 

 outwards. Each ascus contains a definite number of sporidia, 

 which are sometimes coloured. When mature, the asci explode 

 above, and the sporidia may be seen escaping like a miniature 

 cloud of smoke in the light of the mid-day sun. The disc or 

 surface of the hymenium is often brightly coloured in the genus 

 Peziza; tints of orange, red, and brown having the predominance. 



In Phacidiacei, the substance is hard and leathery, intermediate 

 between the fleshy Elvellacei and the more horny of the Sphai- 

 riacei. The perithecia are either orbicular or elongated, and the 



* Tulasne, L. R. and C., "Fungi Hypogaei," Paris; Vittadiui, C., "Mono- 

 graph ia Tuberacearum, " Milan, 1831. 



