10 ANGIOCARPOUS LICHENS. 



Tkibe II. ENDOCARPEtE, Fries. 



Apothecium enclosed in the th alius, closed, perforated, 

 with a distinct, regular, prominent ostiolum ; receptacle 

 entirely thallodal, or changed from the thallus. Nucleus de- 

 liquescent. Thallus horizontal, foliaceous, or crustaceous. 



Genus 1. Endocarpon, Hedw, 

 Apothecium imbedded in the thallus, globose ; nucleus 

 gelatinous, deliquescing ; thallodal receptacle membra- 

 naceous, thin, pale ; ostiolum prominent. Thallus hori- 

 zontal, cartilaginous, foliaceous, subpeltate. 



The structure of the thallus in all the species of this 

 genus is similar. A vertical section exhibits the follow- 

 ing arrangement of parts. The upper surface has a 

 coloured cortical layer, externally darker, of squarish 

 cells, (Plate I. fig. 4, a,) below which is a green layer 

 {b)y irregularly intermingled amongst an hexagonal or 

 rounded-celled medullary layer (c), pale coloured, loose in 

 texture in the upper portion, but denser towards the lower 

 surface, which is bounded by the cortical layer of coloured 

 square cells {a). In some species the thallus is fixed to 

 the substance on which it grows by a central point or 

 callus, from which it spreads on all sides in a peltate form 

 and manner. In other species, the thallus is appressed 

 to the soil, and nearly flat throughout its whole extent, 

 adhering by woolly fibres issuing from the under surface. 

 The apothecia {d) originate in the medullary layer, 

 are at first deeply imbedded, and gradually in maturity 

 rise to the upper smface. Their external covering or 

 tunic {e) is pale coloured, tough, membranous, round, 

 slightly elongated upwards into an obtuse beak or apex, 

 which is smmounted by a dark brownish spot (c), per- 

 forated for the ultimate discharge of the sporidia. 

 Nucleus (/) generally pale coloured, gelatinous, com- 

 prising asci containing sporidia (b).* 



* Fee says that iu Eudocarpon, " Ics sporides sout dispores." 1 have 

 represented them as they appeared to me. 



