MISCELLANE.^. 373 



not perfect his design would expose himself to contempt. This 

 simple fact, that hard veins do cross these furrows intact, ought 

 to be of insuperable difficulty with those who contend for the 

 artificial origin of these circular markings. But there is another 

 appearance shown by these circles which militates just as strongly 

 against their artificial origin. It often happens that two sets of 

 concentric circles impinge or come into contact with each other. 

 In such instances the outer circles of one or the other or both are 

 incomplete. (For examples see Tate's Illustrations, Berwickshire 

 Trans., PL I., V., YIII. ; and Dr. Bruce's Incised Markings, 

 PI. ill., Y., XX., XXII., XXIII., XXVIII., XXX.) This 

 impingement or contact of the circles is easily explained by 

 supposing two lichens growing nearer to each other than their 

 fully -developed size allowed. When the outer circle of one had 

 extended to or reached beyond the periphery of the other a stop- 

 page of the growth of one of them would happen, the more vi- 

 gorous overpowering the other occasionally, and frequently both 

 would suffer. The small size and irregular shape of some of 

 these markings is also more easily accounted for by the natural 

 than by any artificial theory yet proposed. That some lichens 

 do grow, radiating from the centre and forming periodical circles 

 extending in some instances more than twelve inches from the 

 centre, the following extracts will show. 



Lichen centrifugufi, Linn. Sp. pi. 1609: 



Flora Lapponica (1792), tab. XI., f. 2, pp. 357-8. 



''In lichene hoc adolesccnte, pcrount antiqua folia et flores 

 centro proximi reliquentes lapidem, cui inscdobant, fere nudum 

 vel furfure obductum, ut videas quasi ledum circulum ruditer a 

 ])ictorc in lapide depictum." 



Flora Succica, pp. 409, 410. 



''Progrediam a centro ad periphacriam, sensira in medio deli- 

 ([uoscondum, prime intuitu dignoscitur." 



Lichen centHfiigun, Linn. Lightfoot, Flora Scot. p. 814. 



**The centre of tlio circle often consists only of minute fur- 

 furaccous leaves, wliich decay first, wliile tlios(^ in the eircuni- 

 fcronce' still remain and constitute a broad circular bund." The 

 tj. centrifugw*, Lightfoot, is now s(>pnrated from L. centtifuyioi, 



