DicRANACE^.] 141 [Dicranum. 



has yet come before us; it is closely allied to D. Bonjeani, but has aggregated 

 setae like D. majus. 



Several species are extremely variable, and again others are very 

 much alike, so that considerable difficulty is experienced by beginners in 

 their correct determination ; this will be best overcome by a careful study of 

 the areolation of the leaf and of transverse sections of the nerve. 



Clavis to the Species. 



Sect. I. Arctoa. Plants autoicous, radiculose only at base ; leaves lane, -subulate, entire. 

 Capsule small with a tapering or strumose neck. 



Capsule erect, neck tapering. fulvelbim. 



Capsule cernuous, neck strumulose. 

 Capsule short ovate. 



Leaves flexuose patent. schisti. 



Leaves falcato-secund. falcatum. 



Capsule oblongo-cylindric. 



Leaves falcato-secund, lid long-beaked. Siarkei. 



Leaves erecto-patent, lid short-beaked. mollc. 



Sect. 2. EuDiCRANUM. Plants robust, dioicous or pseud-autoicous, tomentose ; leaves 

 lanceolate, the longitudinal walls of their cells communicating by fine pores. Caps, cernuous, 

 cylindraceous, more or less arcuate. 

 Leaves not undulate. 



Sets aggregated, nerve serrated at back towards apex. majus. 



Setas solitary, nerve 4-winged at back above. scoparium. 



Leaves transversely undulate. 



Leaves smooth at back, gradually elongated. 



Upper cells elongated, nerve smooth at back. Bonjeani. 



Upper cells small quadrate, nerve serrate at back above. Bergeri. 



Leaves papillose at back, short and broad, suddenly acuminate, spurium. 

 Sect. 3. Aporodictyon. Plants of medium size, radiculose ; leaves lane. -subulate, their 

 cell-walls not interrupted by pores. Caps, cernuous or erect, cylindraceous, curved or symmetric. 

 Capsule cernuous, curved. 



Leaves patent, quite entire. elongatum. 



Leaves secund, serrulate. 



Nerve | — i- width of base, forming all apex. fuscescens. 



Nerve \ width of base, not excurrent. congcstum. 



Capsule erect, symmetric. 



Leaves curled when dry, nerve vanishing at the serrulate apex. 



Subula short, papillose at back. montanum. 



Subula elongated, smooth at back. flagellare. 



Leaves scarce altered by drying, nerve excurrent. 

 Leaves gradually narrowed into a subula. 



Apex quite entire, elongated ; lower cells incrassate. Scottii. 



Apex quite entire, broken off; lower cells lax, hyaline, viride. 

 Apex serrulate, longly subulate ; lower cells lax, very long. Santeri. 

 Leaves suddenly narrowed into a very long setaceous point. 

 Leaves falcato secund. 



Nerve half width of base, serrate at back. longifolium. 



Nerve -|- width of base, smooth at back. uncinatum. 



Leaves erecto-patent, spinulose at back of point. asperulum. 



Sect. i. ARCTOA Schimp. 

 I. DICRANUM FTTI VELLUM {Dicks.) Sm. 

 Autoicous ; short, densely tufted. Leaves secund, lanceolate- 



