340 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



other matrices. One species was observed by Scliweinitz to 

 be developed on iron which had been heated in the forge only 

 a few hours before. Mr. Mclvor found one on a leaden tank ; 

 and another was found by Mr. James Sowerby in the outer 

 gallery of St. Paul's on cinders. The fact appears to be, that, 

 like Alga3, they derive their nutriment in general from the 

 surrounding medium, and not from the matrix on which they 

 grow. Reticularia umbrina sometimes grows on the hardest 

 wood, where it can derive no nourishment from the matrix. 



2. Trichogastres, Ft. 



Substance at first carnose ; peridium simple or compound, 

 varying greatly in thickness, the outer coat sometimes bursting 

 like a volva, inclosing a convolute hymenium, which at length 

 vanishes, leaving a mass of threads and dusty spores. 



366. Though in a state of maturity there is such a close 

 resemblance between this and the foregoing tribe, in infancy 

 few productions can be more different. While the Myxo- 

 gastres present a pulpy mass, with scarcely any traces of or- 

 ganisation, we have here almost the first intimation of a 

 regular hymenium, except so far as it was shadowed out in 

 Isariacei or Stilbacei ; only, instead of being spread over a 

 definite surface, by the intricate folding and introsusception as 

 it were of the trama or substance from the cells of which the 

 hymenium springs, it occupies the surface of innumerable 

 sinuous folds and cavities, all closely compacted into a crumb- 

 like mass, within one or more external coats. 



367. Within a short compass, few classes present more curious 

 modifications than the genera of which this tribe is composed. 

 On the confines of Myxogastres, we have the little group con- 

 sisting of Coniocyhe, Byssophyton, and a new genus, to which 

 I have given the name of Emericella. These are, in habit, 

 more or less Lichenose, but differ from Calicium and allied 

 genera, in the total absence of asci. Emericella, of which a 

 figure is subjoined, consists of little oblong or clavate masses, 

 varying in colour from yellow to green and grey. A vertical 

 section shows a little peridium above, filled with threads and 

 globose purplish spores, remarkable for a border of long spines, 

 all situated in the same plane. The peridium is supported by 



