221 



Diagnosis: Similar to the preceding, unicolored, laciniae 

 narrow, often connivo-ca.na\icu\sLte, never soralio-maculate, 

 apothecial margins spinulose. 



Description: typical: Thallus fruticose (max. alt. 9 cm.), 

 rigid, chestnut to olivaceous-brown throughout; cortex 

 nitidous, never soralio-maculate; branches bifacial, canal- 

 iculate to connivo-canaliculate, margins spinulose. Apothe- 



FiG. 4. Laciniae of Cetraria tenuifolia. 



da rare, adnate, subterminal, small (max. diam. 5 mm.), 

 convex, disk dark chestnut, spinulose. Spores as in 

 preceding species. 



Contingent phases: {a) much branched above, branches 

 connivent, edges now adhered {— C. islandica var. sub- 

 tuhulosa Fr., Lich. Europ. reform. 37. 1831, C. islandica 

 7 tuhulosa Schaer. Enum. crit. Lich. Europ. 16, 1850). 

 {h) Dark brown to black (= C. Islandica 7 nigricans Retz., 

 ibid., C. islandica f. nigrescens Harm., Catal. Lich. Lorr. 

 171. 1894). 

 (c) Spines long (4 mm.) (= C. islandica ? erinacea Schaer., 

 Enum. crit. Lich. Europ. 16. 1850. 



Substrata: On the earth. 



Distribution: Common in the Boreal and Transitional zones. 

 It occurs from Labrador south to North Carolina (alpine) 

 and westward to Colorado, Montana and British Columbia 

 (eastern slopes). Littoral stations on the Atlantic coast 

 are common as far south as New Jersey. 



Observations: This species, long recognized only as a variety 

 of the preceding species, deserves specific rank as its 

 apothecia are always spinulose and its thallus never 

 soralio-maculate. It was raised to a species by Nylander 



