74 SUMMARY OF CURKENT RESEARCHP:S RELATING TO 



is prefaced by an introduction giving a short account of the structure 

 and biology of lichens. Orders, genera, and species have been re- 

 arranged on modern lines. The changes in classfication and nomen- 

 clature rendered necessary have been explained, and synoptic keys to 

 orders and genera are provided. Large genera have been divided, and 

 the species arranged in definite groups, which should simplify the study 

 of lichen plants. A. L. S. 



New Lichen Genus.— Bruce Fink {Mycologia, 1918, 10, 235-8, 

 1 pi.) has placed in a new genus, Collemodes, the lichen examined by 

 Freda M. Bachman as Collema puJposum. Bachman found in the lichen 

 a new type of reproductive cells. The spermatia are budded from hyphge 

 in the interior of the lichen tissue, and the trichogyne grows towards 

 these groups of spermatia and fuses with one. The lichen is otherwise 

 indistinguishable from Collema pulposwn, but it is not uncommon, and 

 has been collected in several American States. The new species is 

 published as Collemodes Bachmanianum. A. L. 8. 



Lichens of Sand-dunes. — W. Watson {Journ. EcoL, 1918, 6, 

 126-43), in his study of the cryptogamic vegetation of sand-dunes, has 

 made a careful examination of the lichens. On somewhat loose sand- 

 hills the lichens associated with Cyanophyceae, such as Peltigerse, 

 Collemee, etc., are the chief types. Li more stable positions other and 

 varied forms make their appearance, many of them with bright green 

 gonidia. Trees are rare, but they carry a varied lichen-flora, not differ- 

 ing, however, from the tree-lichens further inland. A. L. S. 



Bryophytes and Lichens of Calcareous Soil.— W. Watson {Journ. 

 EcoL, 1918, 6, 189-98) indicates first the lichens that are distinctly 

 calcifuge, then those that grow indifferently on any soil, or with a 

 preference for calcareous substrata. He then gives lists of those found 

 on calcareous walls, on chalk, on limestone grassland, limestone woods, 

 and calcareous rocks, both shaded and exposed. A number of crustaceous 

 calcicole lichens secrete an acid which forms pits in which the lichen 

 fruits are sheltered. A. L. S. 



Notes on the Ecology of Lichens.— R. Paulson (Essex Naturalist, 

 1918, 19, 276-86, 3 pis.) has studied this subject in Epping Forest. 

 He notes the greater abundance of lichens where oaks are dominant than 

 where hornbeam is the principal tree. The latter casts a deeper shade, 

 which inhibits the growth of most lichens. The nature of the soil, 

 whether it be wet or dry, also influences the growth of lichens on the 

 trees. Paulson also adds observations on the longevity and rate of 

 growth of lichens. A. L. S. 



Lichens of a Boulder-clay Area.— The boulder-clay area worked by 

 A. Mayfield {Ipswich and District Field Cluh, 1916, 5, 34-40) is 

 situated in the centre o^ the county of Suffolk. He gives a general 

 account of the lichen-flora of the various associations of trees in the 

 district, with special attention to the kind of bark and of the 



