REVUE BRYOLOGIQUE ^^^ 



* ■ 



nees ; les lanieres, a peu pres de la meme longueur que Ics dents, 

 sunt ouvertes sur la carene ; 2-3 cils longs et noucux. La mem- 

 brane arrive jusqu'au tiers de la hauteur du peristome interne (13). 

 Vanneau est large, double, se detachant facilement de rorifice 



en se roulant vers Fextericur (14). 



La vaginule est cylindrique. - Le iJedicelle est lisse ct long de 



1/2 



Les spores sont petites, de 010-015 --., lisses et vertes. 



Barcelona, Espagne. Mars 1903. 



Dichodontium pellucidum and D. flavescens 



by 11. N. Dixon. 



Being recently engaged in revising the British forms of Dicho- 

 dontium I have met with a number of extremely perplexing plants, 



rendering the treatment of D. flavescens exceedmgly diflicult. 

 I am induced to publish my notes here in the hope that some 

 reader of the Revue may be able either to throw further light on 

 the problem by means ot specimens with which T am unacquain- 

 ted, or to suggest some way out of the dilemma in which v^e 

 appear to be placed in view of the facts I now proceed to give^ 



D. flavescens was distinguished from D. pellucidum more than 

 200 years ago, but Dickson was probably the first to gnc anything 

 like a clear definition of il« distinguishing characters Since hs 



lime microscopical progress has revealed f^^l^^f^^^*^^^!^^^^! '^^"i ' 

 ture, culminating with Lindberg's detection of the d'^e^^enc n 

 the peristome characters, which he describes llms : « renslom urn 

 magnum, multo pallidius, dcntibus allionbus, f^^^^edf ;a"Sus 'S 

 et sublinearibus apice breviler irregulariterque inc s 1 m e- 

 gris, nonnullis inleidum integerrimis, apice proc ssuln n eg^^^^^^ 

 ribus per paris coha^rentibus, infra naedium baud ^^^^S^'^^^^f^^^^^ 



punctato-striatulis, nee apice P^P'^ «^^^' /f t^^. jr/^^rxhl 

 denseque papillosis » [Om Dichodonmm BoL ^^''^^^f/J.^ "J'^^ 

 peristome characters are minutely detailed by Philibert ,n an 



article of this /Zcywe, 1892, p. 9. ^ -k^^ nc »1ip tvnp 



Taking the plant with the peristome thus desc"bed '.s Ih^^^^^^^^^^ 



of D. flavescens we have a considerable sum t^^^l ^^^ ^^^^^^^^^^^ 

 separating the two plants, which for the sake of convenience may 



be tabulated thus : 



/). pellucidum. 



Green or yellowish. 



der. 



HaoTs Ijpically shor., slen- I . Plants normally tall, robust. 



