142 INTRODUCTION TO FUNGI. 



Chapter XIII., on " Geographical Distribution," attempts an 

 estimate of the general distribution of Fungi over the globe, whilst 

 admitting that a very large portion still remains to be explored. 



Chapter XIV. concludes the volume with some observations ou 

 *' Collection and Preservation." 



It is hoped that the volume thus summarised will satisfy the 

 expectations of all who have anticipated its advent, and will fulfil 

 the conditions, and serve tbe purposes for which it was written. 



NOTE ON LECIDEA DIDYMOSPORA, Strn., &c. 

 By the Rev. J. M. Crombie, F.L.S. 



In repudiating my identification of his Lecidea didymospora 

 (" Grevillea," iii., p. 25), it was much to be desiderated in the 

 interests of Lichenological Science that Dr. Stirton, according to 

 the course usually followed by botanists, should have jDointed out 

 in what respect his plant differed fromi. melina (Kphb.). A bare 

 contradiction, affirming only that my identification was "con- 

 jecture," is in such a case absolutely worthless. As will, however, 

 be seen from what follows, there was no " conjecture" whatever, 

 as he is pleased to call it, in the matter, otherwise I should have 

 marked it with [?] as in the case of his Lecidea epiphorhia. The 

 brief description which he gave of Lecidea didymospo7-a was, of 

 itself, quite sufficient to prove the identity to any one who had once 

 read the diagnosis of Megalospora melina^ l^^phb., and left no room 

 whatever for "conjecture." In " Grevillea," ii., p. 60, it is said 

 of the supposed new species that it is, inter alia, minora, " nearly 

 allied to L. sanguinaria, but differing in having two spores in each 

 ascus, which are besides only half the size of those of the latter, 

 and oval in shape instead of oblong." Similarly, the description 

 of L. sanguinaria, var. Melina (Kphb.), given by Nylander in 

 " Lich. N. Gran.," p. 72, and in *' Lapp. Or.," p. 166, is " thecis 

 bisporis, sporis 0-052-64 mm. longit. 0'034-44 mm. crassit." [i.e., 

 nearly half the size of those of the type), adding " nix est nisi 

 forma bispora varietatis (^sunguinarioi) affinis, Seiner." The other 

 and lesser points of difference referred to by Dr. Stirton are only 

 such as may be seen in states of the type. There can thei'efore be 

 no question that the two are identical, and my identification has 

 since been independently confirmed (if such confirmation was 

 needed) by Dr. Th. Fries, in "■ Lich. Scand.," ii., p. 480. Or if 

 any farther question can possibly arise as to the identity, it can 

 only be on the grounds that Dr. Stirton's plant was a 2-spored 

 variety of the type itself, and not of its var. affinis. But even in 

 this case it evidently did not require a new name, since that of 

 Krempelhuber would be amply sufficient for both, forms. As to 

 the specific value attributed to Lecidea didymospora, when it is 



