LICHENS. 165 



rocks, it is difficult to conceive ; and if Dr. Hooker's opinion on 

 the subject be correct, it is evident that we have much to learn. 

 Without descending, however, so low as mosses and lichens, there 

 are in Australia, two instances, one from the animal, and the 

 other from the vegetable kingdom, that seem to open up a very 

 wide field of inquiry. I allude particularly to the shrub called 

 Cmlebogyne ilicifolia, which without any apparent male organs, 

 seems to propagate itself from generation to generation; and 

 also to the troublesome insect called Aphis or plant-louse, which 

 according to Cuvier and Owen, is capable of multiplying in a 

 manner different from the higher forms of animal life, and that 

 to such a degree, that supposing one aphis produced one 

 hundred at each brood, she would at the tenth brood be the pro- 

 genitor of one quintillion of descendants 1,000,000,000,000,000, 

 000. 



The Lichens, which I have collected belong to the following 

 genera: (1) Usnea, (2) Oornicularia, (3) Bamalind, (4) Parmelia, 

 (5) Lecanora, (6) Lecidea, (7) Opegraplia, (8) Graphis, (9) 

 Bceomyces, (10) Cladonia, (11) Collema, (12) Pertusaria, and (13) 

 Verrucaria. 



(1) Usnea. This is a cosmopolitan, and is said to derive its 

 name from an Arabic word, which is a generic term for all 

 Lichens. As it hangs gracefully from the branches of old trees, 

 it is compared by some of our poets to " old men's beards," and 

 by Shakspeare it is called " idle moss." It is said to be a 

 stringent, and in some parts of the world it is collected and pre- 

 served as winter fodder for domestic animals. Usnea has had its 

 reputation as a dye, and also as a remedy for hooping cough, but 

 whatever may be its utility in these respects, there can be little 

 doubt respecting its use to the bird stuffer, and as it is found in 

 almost all countries, from the Arctic to the Antarctic regions, it 

 is [always available for collections of stuffed birds. Although 

 Usnea may be seen on most of our old trees and fences, yet it is 

 not so abundant as in colder climates, where it attains the great- 

 est size, and sometimes covers the surface of the rocks. The 

 species so common here appears to be U. barbata, and is of a 

 greyish colour, but in some parts of the colony it assumes an 

 orange or straw colour ; and it seems probable that one of 

 these varieties has furnished the orange dye to which allusion has 

 been made. 



