Rev. W. A. Leightoii on the Lichens of Spitzbergen. 441 



regarded as reaction at all. He gives a most interesting tabular 

 arrangement of parallel forms in which the leaction does and 

 does not occur : — 



K luteo tinctse colore. 

 CI. endivicefolia. 

 CI. cervicornis. 

 CI. cariosa. 

 CI. lepidota. 

 CI. ecmocyna. 

 CI. pimgens. 



CI. delicata, var. subsquamosa. 

 CL macilenta. 

 CI. rangiferina. 



K non coloratse. 

 CI, alcicornis. 

 CI. verticillata. 

 CI. pyxidata. 

 CI. degeaerans. 

 CI. gracilis. 

 CI. furcata. 

 CL squamosa. 

 CI. bacillaris. 

 CI. silvatica. 



Under CL lepidota, bellidiflora, and cornucopioides respectively 

 two species would appear to be comprised, distinguishable by a 

 different reaction, as we have also ourselves remarked in our 

 testings among the large collections of the Hookerian Herbarium. 



The work is arranged according to a modified Massalongo- 

 Koerberian system. It includes 246 species and varieties, 

 which, if classified after Nylander's system, may be thus dis- 

 tributed : — 



Collemei 8 



Caliciei 1 



Sphserophorei . . 2 



Stereocaulei .... 3 



Cladoniei 17 



Usneei 1 



Ramalinei 5 



Cetrariei 7 



Brought forward 44 



Peltigerei 12 



Parmeliei 17 



Gyrophorei .... 9 



Lecanorei 61 



Lecideei 76 



Graphidei 3 



Pyrenocarpei. ... 24 



Total 246 



Of these the following are described as new : — 



Lecanora coriacea, Gyrophora discolor, Lecidea (Toninia) con- 



jungens, Lecidea [Biatora) coUodea, L. pullulans, L. scrobiculata, 



L. impavida, L. associata, L. (Sporostatia) tenuirimata, L. {Buel- 



lia) vilis, Arthonia excentrica, Verrucaria extrema, V. rejecta, 



V. {Arthropyrenia) conspurcans. 



The learned author has detected a useful chemical criterion of 

 allied species of Lecidea by the application of the solution of 

 iodine to the stratum medullare of the thallus, which by reac- 

 tion it turns of a blue colour in some species, whilst in others 

 there is no reaction. Of this discovery he thus speaks : — " Hanc 

 notam accuratis lichenolosorum studiis enixe commendamus. 



