The Scottish Naturalist 109 



Usnea constrictula sp. nov. — Thallus pallide cinereo-glaucescens 

 rigidiusculus erectus, basi crassiusculus, opacus, ramosus 

 et ramulosus ramulis plerumque divaricatis et sorediosis, 

 articulatus et ibi constrictus sed non inflatus ; axis centralis 

 pergracilis ; fibrillar medullares arachnoidese, K flaventes 

 dein rubentes, I vinoso-violascentes; soredia K — . 



Prope New Galloway (J. M'Andrew), &c. 



There is present, besides, a member of the florida group, 

 whose ramification is, however, more open and straggling, re- 

 sembling in this respect the preceding, but whose pretensions 

 to a specific distinction are more doubtful. In the first place it 

 may be remarked that there are great differences in the thick- 

 ness of the solid central axis. In some it is thread-like, and the 

 surrounding medullary fibres are loosely arachnoid ; in much 

 the larger proportion it occupies the greater portion of the 

 stem, while the medullary fibres are accordingly crushed and 

 rendered compact. Now, how much significance in the way of 

 specific distinction one may legitimately claim for such differ- 

 ences is an open question ; but at any rate, these differences are 

 remarkable enough. 



The present Usnea has a slender axis, and the soredia are 

 not tinged yellow by K. In the group to which it belongs this 

 lichen forms a rare exception to the rule, " Soredia K flaventia." 



Usnea mollis sp. nov. — Thallus pallide cinereus vel pallide 

 cinereo-glaucescens, basi crassiusculus, erectus, ramosus ut 

 in prcecedente sed ramulis longioribus ; axis centralis per- 

 gracilis ; fibrillar medullares K — , I — ; soredia K — . 



Prope New Galloway (J. M'Andrew). 



THE LIFE AND LABOURS OP A SCOTTISH NATURALIST, 



GEORGE DON OP PORFAR. 

 By JOHN KNOX. 



{Continued from page 70.) 



THE next and the only other composition appeared in 18 12. 

 It is an 'Account of the Native Plants in the County 

 of Forfar, and the Animals to be found there,' forming Appendix 

 B to ' General View of the Agriculture of the County of Angus 

 or Forfarshire. Drawn up for the Consideration of the Board of 



