A, L. SMITH! LICHENS. 71 
LICHENS. 
By A. Lorrain Smita, F.L.S. 
Mr. Compton collected about 120 specimens of lichens. A certain number 
were sterile or otherwise undeveloped, but altogether 110 species or varieties 
have been recognized; of these, one genus and 20 species are new to 
science. 
Several lists of lichens from New Caledonia have been published. In 
1861, Nylander issued his “ Expositio Lichenum Novæ Caledonie,” * which 
comprises 104 species. This was followed in 1868 by the “Synopsis 
Lichenum Nove Caledoniz,” f with 220 species or varieties. Müller-Aargau 
at a later date described 73 lichens from Nouméa f, and more recently 
127 different forms from N. Caledonia $. 
About half of those brought home by Mr. Compton were already recorded 
in one or other of these lists, but as all of the collections vary considerably, 
we may conclude that the lichen-flora of New Caledonia is not yet exhausted. 
Our knowledge of lichens—more especially of tropical lichens—is too 
fragmentary to allow of wide statements on distribution ; but enough is 
known to draw some general conclusions. A number of lichens are 
cosmopolitan; a very large number are common to tropical and subtropical 
lands; a few, so far as is known, are endemic in different areas. New 
Caledonia lichens are closely allied to those of Oceania: Stictaceæ are well 
represented ; genera such as Thysanothecium and Heterodea and species 
such as Cladonia retepora are confined to Oceania and are abundant on the 
island. Miiller-Aargau, from his study of Nouméa lichens, concluded that 
air-currents transported the lichens of S. America to Africa, and thence to 
Oceania. The present collection certainly confirms that view. Leptotrema 
and Lepidocollema were until now monotypic genera confined to S. America : 
a second species of the former has appeared in New Caledonia, and a new 
genus, Lepidoleptogium, very closely allied to Lepidocollema has been 
diagnosed. Portions of lichen thalli are not only very light but support 
prolonged desiccation, and would revive after long sojourn in the air. 
The wide distribution of lichens is therefore not to be wondered at: the 
areas of distribution are climatic rather than geographical. 
The specimens from New Caledonia submitted to me were mostly numbered, 
with a corresponding list of numbered localities. There was also a box 
containing sundry unnumbered rock specimens from Mont Montravel, north 
of Nouméa, and there were parcels of specimens from Baie Ouémo, Nouméa, 
also without numbers. I have to thank Dr. Bernt Lynge, Mr. Gepp, and 
Miss Wakefield for helpful suggestions. 
* Ann, Sei. Nat. (Bot.), xv. 1861, 37-54. ` 
t Bull. Soe. Linn. Norm. sér. ii. 1867 (1868), 39-140. 
f Rev. Mycol. xxxiii. 1887, 77-82. 
$ Journ. de Bot. vii. 1893, 51-55, 92-94, 106-111. 
