41 



NEW LICHENS. 



By a. Lorrain Smith, F.L.S. 



(Plate 510.) 



Several of the species of lichens described below were col- 

 lected by well-known lichenologists many years ago, and are 

 preserved in the herbarium of the British Museum. At that time 

 less use was made of the microscope for purposes of determination 

 than in our day of improved optical instruments ; the microscope, 

 however, must always be the final criterion in the case of plants 

 that are classified chiefly on their microscopical characters. Field 

 identification by trained naturalists is marvellously accurate, but 

 mistakes are liable to occur unless constant use is made of high 

 powers of magnification. 



Other species, collected recently, were sent to me on various 

 occasions for identification, and have proved to be of extreme 

 interest. It is with great pleasure that I tender my thanks to the 

 various donors. They will all be included in the forthcoming second 

 volume of the Monogrcqjh of British Lichens, the first volume of 

 which was prepared by the late Rev. J. M. Crombie and has been 

 before the public for som-C years. 



Lecidea pleiospora, sp. n. Thallus tenuis, virescens, indis- 

 tinctus. Apothecia minuta, immarginata, circa 0-250 mm. diam., 

 nigro-fusca, intus rufescentia, disco fusco-rubro ; hypothecio 

 angustato, etiam fusco-rubro ; paraphysibus paucis, gracilibus, 

 conglutinatibus ; ascis oblongo-clavatis, circa 0-075 mm. longis, 

 0-012 mm. crassis ; sporis 12 ad 18 in ascis, globosis vel leviter 

 angulatis,episporiodistincto instructis.hyalinis, 0-006-8 mm. diam. 



Ad terram argillaceam. 



Belongs to the Biatora section of Lecidea, near to L. rubidula. 

 Collected by the Rev. H. P. Reader in November on the soil of 

 a disused clay-pit at Little Bowden, Northants. The thallus 

 becomes a dull dark green when dry. The apothecia are fairly 

 abundant. The species is distinguished from others by the many- 

 spored ascus, and by the irregularly globose spores. 



Verrucaria prominula var. minor, var. nov. Thallus tenuis 

 tartareus, cinereo-albidus vel subfuscus. Pentheciis numerosis, 

 sparsis, minoribus quam typi iis ; sporis ellipsoideis, hyalinis, 

 0-014-17 mm. longis, 0-006-7 mm. crassis. 



Ad saxa maritima. 



Collected at Nanorbee, Tenby, Pembrokeshire, by the late 

 W. Philhps. 



Gongylia Koerb. Syst. Lich. Germ. p. 351 (1855). 

 Thallus crustaceous, not corticated. Agal cells Pleurococcns. 

 Perithecia almost sessile, soft in texture, bright or dark-coloured, 

 with a poriform ostiole ; paraphyses slender, free ; asci 4-8- 

 spored ; spores acicular, straight or somewhat bent, colourless, 

 nuiltiseptate. 



Journal of Botany. — Vol. 49. [Feb. 1911. J e 



