16 



cata, but a smooth, brown, unspeckled under surface. No other 

 local Papery Lichens, except the all-yellow species of Group 9, 

 have conspicuous yellow margins. In outward aspect, 6". crocata 

 and vS". aurata are much alike. 6". aitrata, however, may turn rosy 

 red when dry, and is yellow tvithin, as seen where broken, while 

 ^. crocata is white within. The algal cells in w9. aurata are probably 

 Protococcus. 



Sticta aurata 



A subspecies of C. crocata, requiring no separate description. 

 See C. crocata. 



Nephroma. A genus distinct from our other Papery Lichens 

 in having fruits on the under surface of special marginal lobes, 

 which curl or fold upward to expose them. Fruits, however, are 

 scarce, and for ordinary identification, the other characters must 

 be noted. 



Nephroma resupinatum. Back-Fruiting Lichen 



Growing on the mossy bases of trees, usually in rather deep 

 woods, not common. It forms irregular rosettes up to 15 cm. or 

 more across, with branches up to 1 cm. wide, though usually 

 smaller. Margins are lifted and waved in irregular fashion, often 

 bearing smaller, fan-like lobes. The upper surface may. be gray 

 or brown, sometimes purpHsh, smooth or slightly wrinkled, more 

 or less covered with a very light down. The under surface is 

 covered with a brown, downy nap, on which are found clusters of 

 white, globular tubercles, each usually less than 0.5 mm. diameter. 

 The algal cells are Nostoc in fairly distinct chains. 



Fruits rather rare, up to 1 cm. across, nearly circular, occupy- 

 ing the entire under surface of special lobes or flaps extending 

 from the lifted tips of the branches. Spores brownish, 4-celled 

 or sometimes 6-celled, 19 to 26 by 4 to 7 microns. 



Nephroma resupinatum is the original species from which 

 several subspecies have been segregated. It is the only Nephroma, 

 and in fact the only local lichen with white tubercles on the under 

 surface. These would not be mistaken for the flat or cupped speck- 

 ling beneath species of Sticta. Otherwise N. resupinatum resem- 

 bles Sticta amplissima, diflfering in its darker color, thinner tex- 



