228 Bibliographical Notices. 



are somewhat more sparingly quoted : we would suggest that references 

 should he made constantly to Tuckermann's ' North American 

 Lichens.' The dissections were made under an excellent microscope 

 hy Messrs. Powell and Lealand ; and we have no doubt that the ap- 

 pearances which presented themselves have been faithfully transmitted 

 to us in the present volume. We are sorry, however, to be unable to 

 speak of the execution of the plates with unqualified praise. The 

 lithography is very coarse, and in some cases the letters attached to 

 the figures are almost illegible (see plate vii. and xxiv.) ; the colours 

 also are frequently smeared upon the plates. We trust that better 

 care will be taken with those which follow, and we venture to hint at 

 a few improvements which may be made in them. It would be desi- 

 rable that the aseus should in all cases be figured, where its form can 

 be discovered : and if the size of the drawings were reduced consider- 

 ably, much expense would be saved and no practical advantage would 

 be lost. Whenever the species of lichen, whose analysis is given, had 

 never been figured, or was ill-figured, a representation of the plant of 

 the natural size might be very profitably annexed. 



We will now say a few words on the literary execution of the work- 

 It would have been a great improvement if Mr. Leighton had given 

 specific characters of the Lichens in every case, so that a botanist 

 might be able to determine a specimen from his work, without con- 

 tinually having recourse to other books. To take an example. The only 

 information given respecting the thallus of the first six species of jEWo- 

 carpon (E. miniatum,l eptophyllum, euplocum, Icetevirens, psoromoides 

 and pulchellum) is " thallus foliaceous subpeltate ; " although the 

 thallus alone immediately distinguishes several of these species from 

 each other. Again, between E. miniatum, Ach., and E. leptophyllum, 

 Ach., no distinction whatever is drawn, the description of the sporidia 

 running in exactly the same words for each. According to our notions, 

 indeed, E. leptophyllum is only a dwarf form of E. miniatum, with 

 which Fries associates it ; and this view is much confirmed by Mr. 

 Leighton's discovery, that the analysis is the same for both. Had 

 the work been constructed on a different plan, a small additional 

 amount of labour and expense would have made it a portion of a 

 History of British Lichens, instead of its being simply a very valuable 

 supplement to other works, and one which can only be employed by 

 a person in some degree acquainted with his subject. 



Mr. Leighton is considerably more inclined to divide species than 

 ourselves, and in some cases constructs them out of scarcely sufficient 

 materials. Thus we should hardly have distinguished Chiodecton 

 albidum, Leight., from C. myrticola, Fee (pi. viii. ix.) ; or Verrucaria 

 codonoidea, Leight., from V. margacea, Wahl. Still less certainly 

 does it appear to us prudent, in so very difficult a genus, to describe 

 a new species of Verrucaria {V. linearis, Leight.) from the portions 

 of the plant which grow on the Borrerian specimens of V. Bufourii 

 ( = V. Borreri, Leight.). The plant, it seems, resembles V. Bufourii 

 in almost everything except in the smaller size, and in the differently 

 shaped sporidia. These sporidia appear to us to be in all likelihood 

 simply the young or abortive ones of V. Bufourii : different enough 



