146 



Mycologia 



These probably arose from minute remnants of the thallus left 

 in scraping the central portion of the plant from the rock. After 

 4 years the areas returning over the denuded center had increased 

 in size considerably and were beginning to overlap. After 8 years 

 a dozen regenerated thalli had covered the denuded center, except 

 the portions covered by the regenerated lobes which had grown 

 inward from the marginal zone not denuded to meet and overlap 

 these. The 12 thalli varied from 2 to 5.3 cm. across. At this 

 time the whole area was 32.3 by 40.4 cm. across. 



Kentucky, area 30, 1 m. from the top in a crevice 1.5 m. wide 

 and extending nearly north and south through the face of a high, 

 dry, northward-facing cliff, the crevice shaded, except near the 

 middle of the day. The thalli of Umbilicaria pustulata and 

 Gyrophora dillenn were removed from a circular area 4 dm. in 

 diameter, except a few fragments about 1 cm. across, left attached 

 by the umbilici, and 9 specimens of the former plant of about the 

 same size. Plants of the same species were left about the study, 

 and some of those of Umbilicaria pustulata bore apothecia. 

 After 10 months the fragments showed no evidence of regenera- 

 tion, and the plants left had not grown sufficiently so that any 

 increase in size could be noted. After 4 years 15 plants were 

 found growing in the area ; but it was not possible to determine 

 which might have arisen from regeneration and which might 

 have represented the minute plants left when the study was 

 plotted. The largest plant was 3.8 by 4.2 cm. across, and this 

 and two other plants of Umbilicaria pustulata were sparingly 

 covered with pustules. The other 12 plants were from 0.3 to 2.1 

 cm. across. After 8 years about 40 plants of the two species were 

 found growing in the area. Fourteen specimens of Umbilicaria 

 pustulata averaged 2.5 to 5 cm. across in various directions and 

 were conspicuously pustulate. Six of them showed young 

 apothecia from 0.2 to 0.4 mm. across. Twelve specimens of 

 Gyrophora dillenii were 1.5 to 3.45 cm. across. 



Kentucky, area 13, on top of a limestone rock 0.9 by 1 m. across 

 and 20 cm. high, on a partially shaded, dry hillside, the upper 

 surface of the rock making an angle of 60 degrees with the 

 horizon. All the large specimens of Dermatocarpon miniatum 

 were taken from a quadrat 17 cm. square, leaving many small 



