﻿2.-1 



lichens," and which may attain a length of one-third of a millimetre. 

 At the other end of the scale Calicium with its allies may be noted 

 as having spores only 1 -400th of a millimetre in length. Lecanora 

 is of course by far the biggest genus hitherto dealt with, and con- 

 tains 197 species grouped into seven subgenera which formerly 

 ranked as distinct genera. Six of these are small, and together 

 cover only twenty-six species ; the remainder constitute the su 

 genus Euleatnora, which is itself divided into sixteen groups, son 

 of which have by certain authors been regarded as genera. Attentic 

 may be called to one species which ought to interest the Londone 

 It is L. galactina, remarkable as being the only lichen which ca 

 withstand the pernicious atmosphere of the metropolis ; it grows c 

 composite walls in the more open suburbs, and is not uncommoi 

 The pseudo-genera Variolaria and Isidium of older authors are omitt< 



j been founded merely on degraded s 

 Among the more noticeable features of the volume 

 led the seventy-four very clear woodcuts supplied i 



'^lus- 



tration of the genera. This is method of illuminating the subject 

 which is seldom adopted by lichenologists ; it is therefore the more 

 welcome in the present instance, especially as these illustrations 

 have been specially prepared for the work. The type, the paper, 

 and general appearance of the volume are excellent. Excellent also 

 is the plan of showing at the head of every brace of pages the 

 family, tribe, and genus under discussion. We should like to give 

 a specimen of Mr. Crombie's method of dealing with the species ; 

 but space forbids. Suffice it to say that the description is followed 

 by a full synonymy, valuable remarks of a critical character, habitat, 

 distribution in Great Britain, and the localities of the specimens in 

 the British Museum. 



In conclusion, two passages may be quoted as showing that 

 lichenologists are laying claim to plants which algologists are 

 unlikely to relinquish. On p. 18 Mr. Crombie says : — " Various 

 Scytonemas probably belong to this genus" — Gomonema; and on 

 p. 3d, " There is every reason to believe that some Nostocs are 

 undeveloped states of different species of this and perhaps also of 

 the following genus" — Collema and CoUemodium. ^ q._ 



These Charts and Definitions have been prepared by the Misses 

 :ooke as a summary of the work required for the S. Kensington 

 ilementary) and Oxford and Cambridge Junior Local 



Such charts and tables are often very helpful to a 

 beginner, and those before us are drawn up with care, and contain 

 much condensed information ; but they are not free from inaccuracy : 

 e. g., Pterodoplujta is used throughout for Pteridophyta ; the Eu- 

 phorbiacece are described as monoecious, although one of the com- 

 monest plants of the order, Mercurialis perenms, is dioecious. We 

 fad to understand why annular roots are described as "adventitious " 

 rather than as "true" roots. "Spongioles: The mouths at the 

 extremity of the hairs" is surely unaccountable. Most readers 



