386 Mr. G. H. K. Thwaites on Lichens. 



Polyaclius hiculor, 



P. oblongo-ovatus, convexus, niger, nitidus, capite, thorace pedi- 

 busque rufo-testaceis, antennis fulvis, extrorsum nigris ; thorace 

 remote pimctato; elytris sat fortiter punctato-striatis, interspatiis 

 planis, duobus extemis convexiusculis. 



Long. I lin. 



Hab. Gawler Town, South Australia. 



Vertex smooth, impunctate ; clypeus semiovate, impressed 

 Avith a few remote punctures ; eyes large, subangulate-emar- 

 ginate, moderately distant, black ; anteunaj with the six upper 

 jo'nts slightly thickened, the four outer ones black. Thorax 

 about twice as broad as long ; sides rounded and converging 

 from base to apex ; basal margin slightly bisinuate on either 

 side ; median lobe produced, angulate, its apex rounded, entire ; 

 upper surface transversely convex ; subcylindrical at the apex ; 

 apical and basal margins each bordered with a single row of 

 punctures, disk remotely punctured ; extreme basal margin 

 narrowly edged with piceous. Scutellum narrowly oblong, 

 its apex obtuse. Elytra strongly punctate-striate ; interspaces 

 smooth, impunctate, two outer ones slightly convex. 



Very similar in form and coloration to Bucharis martius j 

 in addition, however, to the structural difference in the antennae, 

 it may be at once known by the different form of the basal lobe 

 of the thorax : in B. martius it is thickened, its apex being 

 acuminate ; in the present insect the lobe is flattened, forming 

 a thin plate, and its apex is rounded. 



[To be continued.] 



XLIX. — Note on Lichens. 

 ByG. H. K. Thwaites, F.R.S. 



My thoughts have been much occupied of late upon the sub- 

 ject of lichens and their development, and especially with 

 reference to the views of Schwendener and Bornet, and of 

 some other botanists who coincide Avith them in advocating 

 the theory o^ parasitism as explanatory of the structural com- 

 position of lichens. 



I have not the least desire, nor have I any intention to 

 impugn tlie correctness of the descriptions and of the beautiful 

 delineations of Mons. Bornet (' Annales des Sciences Natu- 

 relles,' 4^ serie, tome xvii.) ; but I must candidly confess that, 

 after prolonged consideration, I cannot bring myself to yield 



