6 LINDSAY, ON POLYMORPHISM IN LICHENS. 



length and breadth; fre- 

 quently of short, roundish, 

 or oblong, articulated cellules, 

 each of which bears at its 

 apex or side a spermatium; 

 frequently more or less ra- 

 mose, sometimes only at base ; 

 variable. 



2. Size. — " Arthrosterig- 2. Size. — Usually short; 

 mata" frequently long ; va- comparatively uniform, 

 riable. 



The chief forms oi polymorphism, or plurality of fructifica- 

 tion, I have apparently observed in the same species of Lichen 

 are the following : 



1. More than one form of Spermogonium. 



2. More than one form of Pycnidium. 



3. Pycnidia in addition to Spermogonia ; or Spermogonia in 

 addition to Pycnidia. 



4. Pycnidia instead of Spermogonia. 



5. Spertnatia and Sporidia in the same conceptacle. 



6. Different sizes and forms of Spermatia and Sterigmata, 

 or of Stylospores and Basidia. 



Multiple forms of the reproductive organs I have met with 

 chiefly in the lower Lichens, in species, e.g. of the genera 

 Verrucaria, Strigula, Stigmatidium, Trachylia, Calicium, Ar- 

 thonia, Opegrapha, Graphis, Lecidea, Abrothallus, Lecanora. 



But I have found them also in a few of the higher Lichens, 

 e. g. in species of Parmelia, Roccella, Alectoria. 



The following short catalogue of species in which I found 

 deviations from, modifications of, or additions to, the ordi- 

 nary reproductive organs, Avitli an enumeration of these 

 deviations, modifications, or additions, will probably suffice 

 to illustrate the general subject of my present communica- 

 tion, and to indicate the direction in which future observa- 

 tion is likely to prove useful, either by correcting the errors 

 of previous authors, or by confirming and extending their 

 results : 



I. Genus Verrucaria. 



V. Tayloi'i, V. chlorotica, V. nitida, V. epidermidis, 

 V. biformis. Two or more forms of secondary re- 

 productive organs [Spermogoniimi or Pycnidium.] 

 V. gemmata. Spermogonia and Pycnidia. 

 V. glabrata. Two forms of Spermatia and Sterig- 

 mata. 



