APPENDIX TO COUNTER-CASE OF GREAT BRITAIN. 603 



on the rookeries. The skins of the dead pnps that die on the Commander Islands 

 are talcen off by the natives, and a small price is paid for them at the Com])auy'8 

 store. The men examined by me had been recently at the rookeries for the purpose 

 of procuring such skins, and reported that they had got no more than usual, and the 

 agent of the Company corroborated their statements. 



Natural Indications of former extent of Ground occu^ned hy Seals on the Frihyloff Islands. 



While on the Pribyloff Islands in 1892, my attention was frequently called to the 

 yellowish grass {Ghiceria angitntata), which grows in the vicinity of all the rookeries 

 on both St. Paul and St. George Islands. It was asserted by the United States 

 Treasury Agents tliat this yellow grass marked the limit of the ground that had 

 Avithin recent years been continuously covered by seals, which, if correct, would 

 tend to show a very great decrease in seals fre(iueuting the islands during this time. 

 During the entire season, careful note was made of all facts that could have any 

 bearing upon this question. 



I noticed at the time of my first visit to a rookery on St. Paul Island in 1892 (Ist 

 July) that much of this grass-covered ground was dotted with boulders of various 

 sizes, upon which were mature lichens. Even snuill stones that were less than a foot 

 above the ground were completely encrusted by them, affording incontestable proof 

 that even were it admitted that the yellow grass, in all probability, marked the 

 ground upon which seals have been at some time or another, its presence is no 

 evidence that the ground had been occupied by them within recent years. 



The climate of the Pribyloff Islands is in every way suited for the rapid growth of 

 lichens, and every rock and stone that has been undisturbed for a sufficient length 

 of time is covered with them. 



Soon after the ishmds came under the control of the United States an embankment 

 was built at the back of the house now occupied by the agents of the North 

 149 American Commercial Company. It rests upon a base or foundation about 4 

 feet in height, composed of small boulders and broken pieces of stone laid one 

 above the other, but not fastened together by mortar or any other cement. The 

 rough surfaces of these rocks aflord the spores of lichens a much better chance of 

 fixing themselves than the seal-polished rocks near rookeries or hauling-grounds. 



Lichens are now growing on a part of the rocks of which the fouiidation is com- 

 posed, but many of them — the smoother ones — are still quite bare. Only four have 

 on them lichens on which apothecia are apparent, and in these cases they are only 

 partiall}' developed, and many years must elapse before they reach maturity. It is 

 thus evident that under the most favour.able conditions, at least twenty years are 

 necessary for the full development of lichens growing on these islands. The same 

 or closely allied species on the coast of England have been found to require at least 

 twice that length of time to fully mature. 



In 1884, a wall Avas built behind a new store erected hy the Alaska Commercial 

 Company. On a few of the stones of which it is composed lichens are beginning to 

 grow, but there are none th.at show the slightest signs of fructification. In 1885, 

 new embankments were built at both ends of the one first referred to aboA^e, or, 

 rather, it Avas extended in both directions. On none of the rocks at the bases of 

 these recently built embankments are lichens to be seen Avith the exception of five, 

 on which are growing a few small plants Avithout apothecia, and in every one of 

 these cases remaius of old dead lichens are to be found on the same rocks which were 

 doubtless there when the stones were placed. 



It is an accepted fact that lichens increase much more quickly during the early 

 stages of their growth than after they haA'^e begun to nuiture, and while they may in 

 a comparatively small number of years give evidence of bearing apothecia, a much 

 longer time must elapse before they mature. The attention of Mr. J. Stanley Brown 

 and Mr. Towns<ind was called to the lichens growing on rocks on the breeding- 

 grounds, and to there being few or none on the embankments referred to above. Mr. 

 Towusend had collected several specimens of rocks on Avhich lichens were growing, 

 "in order that," as he said, " I may shoAV how soon alter seals have been on the rocks 

 they become covered Avith lichens," but when shown the walls on which no lichens 

 were growing he at once threw his specimens away. 



As more than three-fourths, probably four-lifths, of the ground now covered by 

 yelloAA' grass is also dotted with rocks on which mature lichens are found, it is cer- 

 tain that seals have not been upon such parts of the rookery-grounds for many years, 

 for in dry Ave;ither these lichens are brittle, and would crumble and break off were 

 even a small number of seals to drag themselvesover them, and when a rock is damp 

 a single seal passing over it rubs off all lichens touched by it. Seals driven from the 

 "parade ground" on Reef rookery pass behind that part of it called Garbotch, and, 

 for about 100 yards oA'cr what Avas formerly a part of Garbotch rookery. The rocks 

 at this place have been completely bared of lichens on the sides that are come in 

 contact with by the seals as they travel over them, while on the opi)08ite side they 

 exhibit in most cases lichen-covered faces. 



