UMBILICAKIBL 81 



westward to the Rocky Mountains, Herb. Hook. Also through- 

 out the southern States (passing, there into thinner forms hardly 

 separable from P. Cocoes), from the Carolinas and Georgia, 

 Ravenel, and Florida, Austin, to Texas, Wright. The best- 

 developed and most northern expression of Pyxine ; and I possess 

 it also from Japan, and the Himalayah, as well as from the West 

 Indies, and Java. It was the type of the genus.; but the apo- 

 thecia are properly scutellseform only blackened, the hypothe- 

 cium is well comparable with that of P. picta ; and young apo- 



thecia not yet discoloured occur. * Cuba, Wright ; not yet 



observed here The lichen is only a further development of P. 

 sorediata. * 



Fam. 3. UMBILICARIEI. 



Thallus horizontal, foliaceous, sub-monophyllous, coria- 

 ceous-cartilagineous, more or less blackish-brown ; beneath 

 fibrillose, or now naked ; attached to the substrate at only a 

 single point. 



The family is obviously and strongly differenced from the 

 preceding one ; and yet, through the exotic Omphalodium, Mey. 

 & Flot., Koerb., the two are brought into closest relations with 

 each other. And it is generally allowed that Habit must domi- 

 nate here; however marked the features that might suggest 

 other arrangements. The natural place of the group appears 

 indeed to be between Parmeliei, and Sticta, in the next succeed- 

 ing family. 



The author's explanation of the spore-history of this family 

 may be found in Genera Lichenum, pp. 29, 30. 



* A note by Dr. Nylauder on the chemical reactions with potash ob- 

 served by him in Pyxine may be found in his JEnum. Licli. Husnot, p. 10 ; 

 but I am unable to make use of his results. Here as elsewhere, these re- 

 sults cannot be said to possess any absolute value beyond the portions of 

 thallus subjected to the test; and we have no right either to assume 

 that what we have not examined shall accord with what we have, or to 

 venture on constructing 'new species' out of what does not accord. 



