Rev. W. A. Leighton on the British Umbilicarise. 275 



which the apothecia of the genus are so conspicuous and re- 

 markable. 



So far as my opportunities of research extend, the first writer 

 who mentions these plants is Tournefort, in his Institutiones 

 llei Herbarise, 1710, who describes, in the concise manner usual 

 with earlier writers when treating of Lichens, two species, U. pus- 

 tulata and grisea. Vaillant, following his great master, in his 

 Botanicon Parisiensc, 1727, describes and figures the same two 

 species, with that characteristic accuracy and fidelity for which 

 his plates are so valuable. Micheli, in his Nova Genera Plan- 

 tarum, 1729, makes U. pustulata the sole type and constituent 

 of his 18th Ordo of Lichens, in which the seeds are disposed 

 ^Mn comosa arbuseula" over the whole surface of the plant. 

 These seeds, which are now ascertained to be pulverulent ex- 

 crescences of the thallus, he figures with much accuracy, and 

 also the apothecia, of which however he takes no notice in his 

 description, possibly supposing them to be only the incipients of 

 the fructification which would be ultimately developed into the 

 " comosa arbuscula.^' His tab. 47 represents characteristically 

 a very large specimen in that torn or deeply divided state fre- 

 quently observable when the plants attain considerable magni- 

 tude, and apparently resulting from this excess of growth. He 

 complains that Vaillant^s figure is taken from too small a spe- 

 cimen, but identifies it with his own, having received an authentic 

 specimen from Vaillant himself. Dillenius, in his Historia Mus- 

 corum, 1741, describes at length and figures U. prohoscideay 

 Turn, and Borr., ^me«, Ach., erosa, Hoff"m., arctica, Kch.jjjoly- 

 phylla, T. and B., pellitay Ach., and ^mstulata, Ach. 



Linnseus, in Species Plantarum, 1763, under his section 

 Lichenes Umbilicati includes six species, velleus, pustulatus, pro- 

 boscideus, deustus, polyphyllus, and polyrrhizos» The same ar- 

 rangement is followed by Pollich (Flor. Palat. 1777), Lightfoot 

 (Fl. Scot. 1777), Weber (Spicil. Gotting. 1778), Hudson (Fl. 

 Angl. 1778), Hagen (Tent. Pruss. 1782), Humboldt (Fl. Frib. 

 1793), Retz (Fl. Scand.1795), Withering (Arrang. 1795), Afze- 

 lius (Act. Upsal. 1788), Westring (Act. Sc. Stockh. 1793), and 

 Acharius (Act. Sc,. Stockh. 1794), varying indeed in the number 

 of species described according to the circumstances of theu' 

 respective localities. Hoffmann, in his Plantse Lichenosse in 

 1788 (according to the date on his tab, 2) first uses the generic 

 name Umhilicaria. He figures with inimitable beauty and accu- 

 racy eleven species. This name Umbilicaria was immediately 

 adopted by Baumgarten (Flor. Lips. 1790), Schrader (Spicil. 

 1794), and Acharius (Prodr. 1798). In this latter work it 

 should be mentioned that Acharius refers murinus to the genus 

 Endocarpon. The generic name Umbilicaria is very aptly taken 



18* 



