36 



ward as in typical P. canina. The spores, only 4-celled, and 30 to 

 48 by 5 to 8 microns, are shorter and broader than in other sub- 

 species, whose spores are rarely shorter than 40 or broader than 

 6 microns. The conjunction of all these characters is rare, but forms 

 of P. canina will often show one or more of them. 



Peltigera polydactyla appears to have been named for its 

 clustered, slender fruit-lobes. Its spores also are longer than in 

 other subspecies, 60 to 100 by 3 to 4 microns. Unfortunately the 

 two characters are seldom associated, and there appears to be no 

 sound foundation for the name. 



Peltigera scutata is a subspecies having margins dotted with 

 gray soredia or divided into coral-like growths. Otherwise not dif- 

 ferent from P. canina. 



Peltigera malacea is a subspecies with the under surface mostly 

 brown, and the veins so run together as to be hardly distinguish- 

 able. Toward the tips, small, pale spaces, showing between, suggest 

 the speckling of Sticta scrobiciilata, and specimens not in fruit are 

 sometimes mistaken for the Sticta, even by expert lichenists. The 

 spores are 50 to 72 by 4 to 6 microns, being broader than in any 

 other subspecies except P. horisontalis. They are divided into 4 or 

 6 cells, but never into 8, as most of the forms often are. These 

 characters are not usually associated, and there seems little founda- 

 tion for the name. 



Peltigera rufcscens is a subspecies hardly distinguishable from 

 P. canina, with narrow lobes and crinkled margins. The under sur- 

 face is brown, with darker brown veins. 



Peltigera spuria, also called P. canina var. spuria, is merely a 

 depauperate form, probably due to insufficient shade and moisture. 

 It is usually pale gray, with rather small, usually blackish fruits. 

 The under surface is whitish, with whitish veins and holdfasts. 

 These characters are not particularly distinct, but there is an ex- 

 treme form, P. spuria var. sorediata, also called P. erumpcns, that 

 requires separate description. Instead of the branching, rosette 

 habit of growth, it is often seen as almost unconnected, roundish 

 lobes, with margins curled upward. These may be deeply saucer- 

 shaped, and sometimes less than 1 cm. in diameter. The upper sur- 

 face may be pale gray or brownish, spotted with oval patches of 

 blue-gray, granular soredia, each up to 5 mm. across. The imder 

 surface is whitisli. with a few whitish veins and holdfasts. It will 



