32 LINDSAY, ON ABROTHALLUS. 



forms of reproductive organs in lichens which have been 

 hitherto discovered and described. 



Tulasne describes the five following species of Abrothallus^ 

 viz. : 



1. A. Smithii. 4. A. oxysporus. 



2. A. Welwitzschii. 5. A. inguinans. 



3. A. microspermus. 



It appears to me that, probably from an examination of a 

 limited number of specimens, Tulasne has created an unne- 

 cessary number of species^ which 1 think admit satisfactorily 

 of being reduced to two. The reasons which lead me to 

 propose such a reduction will appear more fidly in the sub- 

 sequent analysis of the structure and character of the species, 

 so far as I have been enabled to examine them in Scotch_, 

 Welsh, and English specimens. Meanwhile, I would state 

 here that Tulasne does not appear to have made sufficient 

 allowance for differences in minor characters produced by 

 variations in habitat, when we consider that the Abrothalli 

 grow on lichens so opposite in their habits as Parmelia 

 saxatilis, P. caperata, P. conspersa, P. oUvacea, P. tUiacea, 

 Sticta fuliginosa, Sticta syhatica, and Cetraria glauca. 1 

 cannot regard the characters on Avhich he has founded the 

 differentiation of the first three species above mentioned as 

 sufficient or satisfactory. I shall, therefore, include them 

 under the same species, to which I shall retain the name of 

 the first — A. Smithii. But, while Tulasne' s characters are 

 insufficient to separate the lichens which he describes as 

 species, they are, to a certain extent, characteristic of 

 varieties. The more prominent of these characters, so far 

 as they accord with my own observations, I propose to 

 preserve under the varieties a, ater, ft, pulveindentus, and h, 

 microspermus, of A. Smithii. The fourth species, A. oxy- 

 sporus, appears a most natm'al one. The fifth species, A. 

 inguinans, which Tidasne designates a "species recedens," 

 I would discard as not properly pertaining to the genus 

 under consideration. It appears more to belong to Celidiiun 

 or an allied genus. It differs from the two species of 

 Abrothallus hereafter to be described — 1st, in its apothecia 

 being superficial or epithalline, and not bursting through 

 the cortical layer of the matrix; 2d, in these apothecia 

 being minute and arranged in orbicular patches, the central 

 ones confluent in deformed maculae ; 3d, in the form of 

 the spores, wliich more resemble the oval stylospores of tlie 

 other species ; and 4th, in its occurring on a tartareous 

 thallus, the sterile crust of a Bajomyces. In the description 



