322 



LICHEXACEI. 



[UMBILICAKTA. 



4. UMBILICARIA 



Hoffm.Fl.Lich.(17!:»5) 

 p. 109 pro parte ; Xyl. 

 Flora, 1875, p. 3u3. 

 — Thallus efribrillose 

 beneath. Apotheoia 

 lecanoroid, with thai- 

 line receptacle, con- 

 taining no gonidia ; 

 hypotheciiim brown- 

 ish-black; spores soli- 

 tary, 2na3 or Suae, 

 brown or colourless, 

 murali-locular or sim- 

 ple ; hyraenial gela- 

 tine bluish and then 

 wine-red with iodine. 

 Spermogones some- 

 what prominent ; sper- 

 matia short, cylin- 

 di'ical. 



Formerly distinguish- 

 ed from the foUowiug 

 genus by different au- 

 thors on insulhcient 

 grounds, this has bi-en 

 detiuitely separated by 



Nylander on accouut of r.j.mearia pnslnlata Hoffm.- 

 the peciihar type of the thallus, x200. b. Vertical 

 apothecia. These are 

 iu a certain way kca- 

 norine, but not truly so ; 



^•->>.- 



Fig. 53. 



-a. Vertical section of 

 section of apothecium, 

 X 30. c. A theca and paraphvsis, X •3r)0. d. Two 

 spores, x5t0. e. Vertical sectin of thallus with a 

 sperniogone, XoO. /. Sterigmata and spermatia, 

 X500. 



for though they present 

 externally a thalline re- 

 ceptacle composed of the cortical and medullary layers, they do not con- 

 tain gonidia (vide Nyl. Flora, I. c). As to the structure of the thallus, 



will be seen from fig. 53 « that this consists of four layers. These 

 are — (Ij an epithalline layer more or less developed or evanescent 

 (whence the presence or absence of pruina on the upper surface) ; (2) a 

 corticali-gonidial layer, the gonidia occupying the lower half of the more 

 darkly delineated portiou ; (3) a white medullary layer; and (4) a cor- 

 tical layer on the uuder surface, of which the upper portion is chondroid 

 (sometimes partly wanting) and the lower (blacki.^h) cellular (cfr. Xyl. 

 Flora, /. c. '). The spermogones have the spermatia in all the species of 

 nearly the same size, viz. 0,004 mm. long, 0,001 mm. thick. 



The genus is divided into two subgenera, founded upon difl'erences in 

 the cortical texture. 



8ubgen. 1. LASALLIA Mcrat (Fl. Par. (1836) p. 202 pro parte). 

 — ThaUus papulose above, lacunoso-foveolate beneath, internally 

 with the chondrohyphre wanting in the lower concave portion of 

 the pustules. Apothecia with the spores solitaiy or 2nai, murali- 

 dividcd, brown. 



