THE DETERMrX.lTrOX OF LrCllEXS TX THE FIELD 7 



59. Ap. with thalline margin. Sp. 8 or many in 



ascus (50. 



Ap. without thalline margin, Sp. 8 in ascus, 



colourless G[. 



GO. Th. ±appressed. Sp. small, colourless, many 



in ascus. On rocks \ Acarospora. 



Th. usu. iiimbricate. Sp. 1-septate, colour- 

 less, 8. On rocks or ground (P. holophcea 



and P. leucospeirea) Placolecania {u). 



Th. isidioid-squamulose. Sp, 1-septate, brown, 



8 in ascus. On trees. Kare Rinodina isidioides. 



01, Sp. simple. Th. variable in colour ; squam- 



ules often discrete Lecidea (Psora) (.s-). 



Sp. 1-septate. Th. +glaucous-grey, thickish 

 and rounded (P. codruleonigricans and 



P. Candida) Biatorina. 



Sp. with 3 or more septa. Th. greyish or 



brown 02. 



62. Sp. fusiform, about 4 times as long as broad, 



3 or more-septate Bilimbia (z'). 



Sp. acicular, more than 10 times as long as 

 broad, pluriseptate (P. pulvinata and P. 

 2Jolysita) Bacidia. 



{a) When Cladonia and Stereocaulon have no apothecia on the 

 podetia they will come in Group B. They may also come in Group C 

 when the th. is granulose. If they are sterile and without podetia 

 they cannot be determined by the key, though they have a peculiar 

 facies which usu. enables them to be recognised. 



(S) 4 mm. is only an approximate measurement and sometimes 

 plants with a large thallus (10 cms. or more in diameter) may be 

 included here, though the majority of the individual lobes may be 

 less than 4 mm. Many plants (e. g., Loharia pulmoiiaria, Ricasolia 

 amplissima, B. Icetevirens^ Peltigera canina, Parmelia perlata, 

 P. sco7'tea) included here may have a thallus exceeding 20 cms. in 

 diameter. 



(c) A spore is said to be muriform when it has longitudinal as 

 well as transverse divisions. In order to see the true septation of a 

 spore it is often necessary to treat the microscopic preparation Avith K, 

 otherwise simple spores with two or many globules j^resent in them 

 may be mistaken for 1-septate or muriform spores respectively. 



{d) The species of Lejotogiiim which would be referred here are 

 those numbered 21-25 in A Monograph of British Lichens by 

 Miss A. L. Smith. In other cases where numbers are given they 

 refer to the numbers prefixed to the species in that work, which should 

 be consulted for further information. In some cases the names given 

 in the Monograph are used, though other views as to nomenclature 

 may be held. Large specimens of L. scotinum and L. lacerum may 

 also be referred here. 



(e) Umbilicate. Affixed to the substratum by a central point. 



(y) Pustulate. With many swellings and depressions. 



{g^ Loharia and Loharina have pale swellings beneath, which 

 must not be confused with pseudocyphelhe. 



