ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 387 



Erichseu criticizes Kajanns' theory that soredia and isidia are 

 merely growth-conditions of lichens, and are therefore valueless as 

 diagnostic characters. Though in abnormal conditions many lichens do 

 occasionally form these bodies, yet in normal positions with customary 

 illumination, etc., both isidia and soredia are, he found, specifically con- 

 stant in occurrence and in form. 



A long note is published on the distinction between Ramalina scopu- 

 loram and R. cuspidata, both inhabitants of maritime rocks distinguished 

 only by a difference in the reaction of the thallus to potash. Erichsen 

 has found, as others have done, that in most cases the reaction is not to 

 be depended on. In none of the specimens could he induce the deep 

 red colour stain that was found by Zopp in the medulla of R. scopulorum. 

 He includes both species under R. cuspidata. 



Additional tabulated lists are given of those lichens that were found 

 on the various habitats, and a bibliography of the literature consulted 

 in the progress of the work. 



Lichens from Brazil.* — Bernt Lynge publishes his study of the 

 Parmclise that were brought home by the Regnell expedition from 

 Brazil. He establishes one new genus, Pseudoparmelia, distinguished 

 by the presence of cyphella; on the lower cortex. There are 70 species 

 of Parmelia, all of them fully described from the author's examination 

 of specimens : -a number of them are new to science. In the introduction 

 there is an extended account of the thallus and peculiar structure of the 

 genus. Lynge gives high systematic importance to the pycnidia which 

 are very constant in this group. He discusses the occurrence of isidia 

 and soredia, which he finds now present now absent on specimens of the 

 same species growing side by side, so that they cannot be mainly due to 

 climatic conditions. Outgrowths from the thallus he considers of minor 

 importance, as they are generally due to some accident of habitat, etc. 

 When combined with other characters, such as the perforations in 

 Parmelia vittata, they are of diagnostic value. He found that a number 

 of species were inhabited by aerial algre : they are to be considered as 

 accidental or occasional parasites. Parasitic fungi are not uncommon ; 

 on one species a fungus was always present within the base of the rhizinai. 

 A constant distinction among species is the appearance of the upper 

 cortex as to whether it is cracked or continuous. A special account is 

 therefore given of the mode of formation of that cortex. In several 

 species he observed that gonidia strayed in small groups into the upper 

 cortex, without however bursting out as soredia ; they can be detected as 

 small green points by wetting the surface. Notes and descriptions are 

 given as to the anatomical structure of the apothecium : great value is 

 given to the form and structure of the paraphyses, though caution is 

 necessary to make sure that fully developed organs are under observa- 

 tion. Chemical reactions Lynge considers most helpful as subsidiary 

 diagnostic characters, but they can only be supplementary to morpho- 

 logical features. A copious bibliography is given, and an index to the 

 species. The plates illustrating the new species are from photographs. 



* Ark. Bot., xiii. No. 13 (1914) 172 pp. (5 pis.). 



