216 NORTHERN TIT. 



sometimes near villages and farms, and we even see 

 tliem in leafy plantations; but they are found principally 

 in the fir forests, and here it is more common than 

 palustris. I therefore stick to the opinion I have 

 previously given about them, and shall do so until 

 proof is adduced that horealis is only the northern form 

 of palustris. I do not know how the note can be so 

 dissimilar. One thing is certain — they are two differ- 

 ent forms. Each person may, after all, agree about 

 their being different species, or not. 



"Professor Middendorff, of St. Peters;burg, to whom 

 I sent specimens of both, and who only met with 

 borealis in Siberia, considers it only a variety of 

 palustris. Probably he has never seen them together in 

 a free state, nor heard the difference in their notes. 

 When I first shewed Professor Nilsson P. borealis he 

 directly found the specific difference striking. So 

 much can opinions vary in such cases, that before 

 forming a decided conclusion, we must have before 

 our eyes those forms about which there can be no 

 doubt that they are those of which we are reasoning-. 

 P. horealis is as distinct from P. palustris as Sylvia 

 ahietina is from S. trochilus, S. arundinacea from S. 

 palustris, S. philomela from S. luscinia, S. hypolais from 

 S. polyglotta, etc., although it is less distinct from P. 

 palustris than is P. sibiricus. The only thing which 

 can make less sure its title to specific rank, would be 

 if it could be shewn that P. palustris towards the 

 north by degrees receives as well the same apparel 

 as the same call-note. This is an interesting question, 

 which naturalists should endeavour to find out. 



"Upsula, Nov. 11th., 1855. T. Lilljeborg." 



The following are the measurements of my specimen 



