528 HOOKER, BOOTHIAN PLANTS. 



L. frustulosa, Ach. Port Kennedy. Scarce. 



L. cerina, Ach. Port Kennedy. Scarce. 



L. ventosa, Ach. Port Kennedy, Lievely, and Cape Osborne. 



L. \itellina, Ach. Port Kennedy. Scarce. 



Lecidea vesicularis, Ach. Port Kennedy. Scarce. 



L. lapicida, Fries. Port Kennedy. 



L. rupestris, Ach. Port Kennedy. 



L. globifera, Ach. Port Kennedy. 



L. petraea, Ach. Port Kennedy. 



L. geographica, Ach. Port Kennedy and Cape Osborne. 



L. alpicola, Wahl. Port Kennedy. Universal. 



Urceolaria scruposa, Ach. Port Kennedy. 



I append a resume of the important observations made by Dr. 

 Walker on the temperature of the air and earth, and the average 

 covering of snow ; and, to render them more complete, I have 

 extracted and meaned the monthly temperatures of Boothia, of 

 from three to four years' observations, published in Sir John Ross's 

 " Voyage." The observations of these officers correspond to a 

 remarkable degree, the approximate mean annual temperature, 

 according to Ross, being + 2° '5, and by Walker (interpolating 

 August as 28°) 4 l°-0. The high mean temperature of the soil 

 at 2 feet 2 inches depth is very remarkable, and that of the 

 surface of the earth below the snow, which depends much on 

 the temperature of the subsoil, and is of great influence upon 

 the vegetation, is still more remarkable. 



Appendix.— Observations at Port Kennedy on the Tempera- 

 ture of the Soil, &c. By Dr. Walker. 



On the 14th September 1858, so soon as it appeared probable 

 that we should winter at Port Kennedy, I sunk a brass tube 

 2 feet 2 inches vertically in the ground, and inserted a padded 

 thermometer. 



The ground at the time of sinking the tube was frozen from 

 6 inches below the surface, and it was with great difficulty that I 

 <jould get the tube sufficiently far down. The soil (surface) was 

 similar to that strewn over land, but from below 6 inches it was 

 of a yellowish mud. The thermometer used was one of very small 

 bore, with a long stem finely graduated (it had been prepared for 

 taking the temperature of trees). 



From the 18th to the 29th September no register was made, as 

 the ship was not in port ; also from the 10th to the 28th March 

 1859, as I was absent from the ship, travelling. The minimum 

 temperature registered was -|- 0*5, on March lOth, 1859. The 

 lowest may be assumed at zero, on the 16th March. 



The register was continued until June 18th, when water entered 

 the tube, and the thermometer was frozen to the side, so that it 

 could not be detached. Column 2 gives the register of the 

 thermometer. Column 3 gives the depth of the overlying snow, 



