NEW BARE Oil CRITICAL LICHENS 109^ 



This form corresponds to var. fornwsiom (Acli.) Nyl., and appears to 

 be fairly frequent. Crombie {British Lichens, j). 45) erroneously 

 gives the reaction with iodine as reddish; on p. 46 he says that 

 C. tenax (I -f- reddish) can be distinguished from C. pidposiim by the 

 reaction with iodine, thus showing that the reaction given on p. 45 is 

 a mistake. C. compactum Ach. is given as a synonym for C . imljposnm 

 form compactiDu Nyl. by Crombie (/. c). Harmand (Lich. de Fr.) 

 states that the plant of Acharius is C tenax, so that if the British 

 plants really belong to C. pulposum, the name compactum ought not 

 to be given to them. The variety pulposiiluni Nyl. ( = C. pulposulum 

 Nyl.) is not O. pulposulum (Wedd.) Harm. Nylander's name has 

 priority (1864) to Weddell's (1869), so that the naming in Crombie 

 is correct and the plant given as C. pulposulum in Harmand's Lich. 

 de Fr. (p. 84) has no right to that name. 



C tenax and C. crispum are united together under the name of 

 C tefiax by some continental authors. There appears to be much 

 justification for this course, since the only practical difference appears 

 to be that the apothecial margin is crenulate in C. crispum, and 

 entire in G. tenax. The thalline characters in plants with entire 

 margins to the apothecia are variable, whilst those of plants with 

 crenulate margins to the apothecia are similarly variable, and on the 

 same plant apothecia may be entire or crenulate, A.^ Lichen tenax 

 Sw. (1784) is an older name than Lichen crispus Ach. (1798), 

 C. tenax should be retained ; C. crispum may be considered as a form 

 of it. Knowing the difficulties of dealing with species of Collema, it 

 is in no spirit of carping criticism that 1 have derived some amuse- 

 ment from the varying descriptions and synonyms of C. multiflorum 

 var. palmatum Hepp. According to Crombie (p. 47) this equals 

 C. tenax var. coronatum Koerb. ; according to Harmand (p. 87) it is 

 also equivalent to his var. palmatum of C. tenax ; therefore var. coro- 

 natum Koerb. and var. palmatum Harm, must be the same plant : 

 but the descriptions do not coincide. Harmand also gives Lichen 

 palmatus Huds. as a synonym for two entirely different plants — on 

 p. 87 for C. tenax var. palmatum and on p. 113 for Leptogium 

 palmatum^ the latter being correct. Crombie (p. 47) adopts a better 

 course in rejecting the varietal name of palmatum, since it might be 

 confounded with L. palmatum. 



C. c/laucescens Hoffm. may occur on sandy or calcareous soil. 

 Sandy hedgebank, Dinnington, S. Somerset (5) ; sand of dune-slack, 

 Braunton, N. Devon (4). 



C. aggreyatum (Ach.) Nyl. Braunton (4), Staple Fitzpaine (5). 



O. chalazanellum Nyl. has not previously been recorded from the 

 British Isles. It is similar to C. chalazanum Ach. but the thallus is 

 much smaller, the apothecia are less than 0-2 mm., and the spores are 

 also smaller (12-19 x 6-10 /u). It occurs on the thin soil-cap of a 

 limestone wall near Taunton (5). 



C. melcenum Ach. According to Crombie a wine-red coloration is 

 given by iodine to a thin section of the thallus. Harmand says there 

 is no reaction with iodine. A number of plants tested give no red 

 coloration. The plant is named C. multijidum by Schaerer in Enum. 



