534 DR LAUDER LINDSAY ON NEW LICHENICOLOUS MICRO-FUNGI. 



II. Coniothecium lichenicolum. 



A. Parasitic on thallus of Lecanora tartarea, L. 



(a) Morchone, Braemar, Aug. 1856, W. L. L. — On isidioid, sterile states of the 

 thallus of the Lecanora. Spores deep brown ; sometimes spherical and simple ; 

 frequently 8-shaped (didymous) ; frequently also in moniliform chains, as in 

 Torula liclienicola, or in groups of four or three. 



B. Parasitic on thallus of L. parella, Ach. 



(a) Blackcairn Hill, near Newburgh, Fifeshire, May 1858, W. L. L. — On sterile 



forms of thallus of the Lecanora. Parasite more irregular in surface and out- 

 line, more crowded, and more frequently confluent than is usual. Occurs in 

 groups on different parts of the thallus of the host. Spores sometimes 8-shaped 

 (didymous), -00025" broad, -0005" long; more generally single or simple and 

 spherical, about -00016" in diameter. 



(b) Morchone, Braemar, Aug. 1856, W. L. L. — On sterile states of thallus, spar- 



ingly scattered, sometimes only about periphery of thallus. Parasite has 

 sometimes an apothecioid aspect, its black mass being girt with an obscure 

 thalline ring. Occasionally it appears as if seated in thalline verrucse, and is 

 so small as to resemble spermogonia. At other times it resembles the smaller 

 urceolate apothecia of Lecanora cinerea ; and if the thallus of L. parella were 

 more generally covered with the parasite, it might, at first sight, be confounded 

 with a form of L. cinerea. 



(c) Glen Dee, Braemar, Aug. 1856, W. L. L. — On isidioid states of thallus. 



Parasite mostly large and flattish, with very ragged outline in the old state, 

 resembling spots of soot ; in young state, is regularly papillar. Has a close 

 resemblance to Spilomium Graplddcorum, Nyl., in size and irregularity of out- 

 line and surface. 

 C. Parasitic on Isidium corallinum, Ach. 



(a) Old Wall, Craigie Hill, Perth, May 1856, W. L. L.— The surface of the thallus 

 shows little distinction between the constituent isidia, which are so closely 

 aggregated as to form a general white subcretaceous mass, sometimes obscurely 

 divided into areola?. Parasite occupies generally the centre of these areolae 

 where they occur, or is studded generally over surface of thallus, as black, 

 round, convex masses, varying in size. Spores in all cases show double 

 contour ; in age acquire an irregular or corrugate outline ; colour generally 

 brown, or blackish-brown, graduating into olive ; sometimes very pale or almost 

 colourless in young state. 



It appears to be the same parasite which occurs on Isidium corallinum in 

 Mougeot and Nestler's Exsic. No. 74; which Isidium is there probably refer- 

 able to Lecanora parella. The parasite resembles black apothecia, which have 

 been doubtless by lichenologists of the pre-microscope era mistaken for the 

 "fruit" of the Isidium or Lecanora. 



The columns of Isidium corallinum have apices that are frequently coloured 

 more darkly than the body of the isidia ; which coloured apices were often 

 mistaken by the earlier lichenologists for apothecia or " fruit" of different kinds, 

 and which often have a close resemblance to some forms of spermogonia. The 

 plant consists, when typically developed, of a series of minute, round, perpen- 

 dicular columns, which become by close appression sometimes subangulose, 

 and may even lose their individuality, coalescing into a general subcretaceous 

 mass, y to |" thick. Where such coalescence does not take place, there is seen 

 on cross section, either natural or artificial — a honeycomb-like arrangement of 

 columns — similar to the basaltic columns of Staffa or the Giant's Causeway on 

 a microscopic scale. Where the apices are not cut off by natural cross section 

 or erosion, they are discrete and papillaeform, resembling, on a small scale, the 

 young ramuscles of Spliteroplioron, as these are figured in my "Observations 

 on New Zealand Lichens " (PL Ixii. fig. 5).* The colour of the isidia varies 

 considerably ; sometimes, especially in specimens long preserved in the 



* Transactions of Linnean Society of London, vol. xxv. 



