260 PROCEEDINGS OF SECTION D. 



The individual specimens of Stictaceae are in some places so 

 very numerous that the trees in the forests have a very peculiar 

 appearance, especially in the forests at Ohakune, New Zealand, and 

 in some parts of Tasmania, where I found the branches and trunks 

 of the trees thickly clothed with these large foliaceous species, 

 varying from about an inch high in some of the smaller species to 

 upwards of 18 inches across in others, so that we can quite under- 

 stand why Drs. Hooker and Taylor (25) termed them " the Patri- 

 cians of Lichens," and can also agree with Dr. Nylander in that the 

 " highest point in the classification of Lichens has been reached " 

 in this group or family of plants. 



The Structure of Stictace.e. 



The study of this family is very difficult, owing to the immense 

 variation in the lobation of the thallus. It is in general a flattened 

 leaf-like expansion, whose texture or consistence according to its 

 thickness and the arrangement of its cellular tissue is membrana- 

 ceous, coriaceous, or cartilagineous. The margins of the thallus 

 are variously divided into segments, which, according to their size, 

 are termed lobes or laciniee, the former being typically broadish 

 and rounded, the latter narrow and usually linear. The upper 

 surface of the thallus of several species may be perfectly smooth, 

 while in others it is roughened with granular soredia or isidia. Occa- 

 sionally we also find that the margins of the thallus are thickly 

 covered with very minute squamules, which give them a very 

 peculiar appearance, especially when these squamules are bursting 

 with their yellowish, whitish, or leaden-coloured granular contents. 



In several species, such as Lobaria puhnonaria, Sticta foveolata, 

 and 5. cellidifera, the upper surface is deeply indented and then have 

 a peculiar reticulate or lacunose-appearance. On the upper surface 

 we also find more or less blackish or brownish-coloured little pimples, 

 these are termed the spermagonia, and are variously scattered on 

 the margins of the foveolffi or irregularly over the thallus, and in 

 some species are chiefly confined to the marginal-lobes. 



The Apothecia, in which the asci or bags are contained, are 

 usually filled with eight colourless or brownish-coloured one-or- 

 more-septate spores. These are likewise irregularly scattered over 

 the surface of the thalline margins of some species, while in others 

 they are strictly confined to the margins of the lobes, and are usually 

 of a chocolate-brown or sometimes nearly blackish colour. 



The under-surface of the thallus is covered more or less with a 

 spongy mass of whitish or brownish coloured fibrils known as 

 rhizincce, which act as rootlets in holding the plants to the decor- 

 ticated bark of trees or mossy rocks or earth upon which they are 

 found, but they differ from rootlets in that they do not take upon 

 themselves the functions of rootlets as in the higher classes of plants. 



Intermingled with the rhizineae, and either thickly or thinly 

 scattered on the under-surface of the thallus, are minute whitish, 

 yellowish, or leaden-coloured spots, or in the case of the genus 

 Lobaria the under surface mav be nearly smooth or more or less 

 covered with bulges or naked gibbi. 



