20 Wheldon : Key to the Harpidioid Hypna. 



this in the absence of specimens, nor have I included Dre- 

 panocladus furcatiis Roth, which, as Monkemeyer ^* has 

 pointed out, is Limnohinm ochracenm var. uncinalum, a plant 

 which has more than once been sent to me as a Harpidium by 

 British collectors ! The forms of Cratoneuron are also con- 

 stantly sent as ' Drepanocladus,' etc. They are so often 

 confused with the other Harpidia, that it seemed desirable to 

 include them in the key. I should imagine that all our herbaria 

 contain C. falcatum labelled ' Hypnmn vernicosum,' although 

 almost the only feature they have in common is the plication 

 of the leaves. 



A word is perhaps necessary on taking up herbarium 

 specimens of these plants. They should be carefully collected 

 in fair quantity, and as mature and representative as possible. 

 It would be possible to pick out abnormal, juvenile or seasonal 

 growths which could not be accurately named. In the her- 

 barium they are misleading, unless accompanied by more 

 characteristic shoots, which may nearly always be found. 



Finally the " Key " is not intended to take the place of 

 the descriptive handbook, but rather to act as an index. 

 Unfortunately the literature on the subject is very scattered, 

 so to facilitate the student's work, when he has found the 

 probable name of his plant by aid of the key, a reference is 

 given to the original description in the List, and to the pages 

 in Dixon's ' Handbook of British Mosses ' and Braithwaite's 

 ' British Moss Flora ' for such varieties as are quoted therein. 



KEY TO GENERA, SPECIES AND MINOR FORMS. 



1. Alar cells not forming distinct auricles, or if auricled, leaves 

 obtuse and apiculate (2). Alar cells wider, forming more or less distinct 

 and often decurrent auricles (3 ) . 



2. Nerve short and forked, double, or none : leaves broad and 

 concave (A) Scorpidium. Nerve longer, single : leaves entire, narrowly- 

 acuminate (B) LiMPRicHTiA. Some aberrant forms of Warnstorfia 

 have the leaf auricles obsolete, but the margin is denticulate, and rhizoids 

 occur at the back of the leaf apex occasionally. 



3. Leaves toothed and plicate : perichaetial leaves longly convolute, 

 making the perichaetium very prominent : cortical cells of stem inflated : 

 inflorescence autoicous (C) Sanonia. Perichaetium less prominent : 

 gtem cortex not differentiated (4). 



4. Stem clothed with rhizoids and paraphyllia : leaves distinctly 

 plicate and strongly nerved : capsule annulate : inflorescence dioicous 

 (D) Cratoneuron. Paraphyllia rare, or none : stem not rhizinose : 

 leaves not plicate — sometimes lightly striate (5). 



5. Leaves entire : capsule annulate : inflorescence dioicous 

 (Drepanocladus). Leaves normally serrate : capsule exannulate, 

 inflorescence monoicous or dioicous (Warnstorfia). 



{To be conlinued). 



Naturalist 



