b OCCURENCE OF ROCK PTARMIGAN PIERS 



On the other hand it may b^ said that as long as we know- 

 so little about the fundamentals of specifity, the difference 

 between species must be the present conventional and necessarily 

 somewhat arbitary one of non-intergradation; and until in- 

 tergradation has been actually demonstrated, we have to give 

 the two forms full specific distinction no matter how slight the 

 difference may be, and even if it leads us into what seems to 

 be an obvious error. 



We can only hope that someone will soon undertake to 

 collect a sufficient number of specimens of the so-called L. 

 zvelchi and of L. rupestris, to be in a position to definitely settle 

 the specific or sub-specific status of the former. Careful com- 

 parison of many specimens would doubtless demonstrate that 

 it intergrades with the mainland phase through individual 

 variation at least. 



Provincial Museum, Halifax, N. S., 

 5th January, 1923. 



