P ETC MORA 525 



But there still remains ornithologically unexplored a great 

 tract of country — forest-land and tundra — eastward to the 

 Ural. With these great gaps still existing, a minutely 

 accurate knowledge of the distribution of birds of North 

 Eussia is not possible. It is hoped, however, that the 

 papers now in preparation will prove useful stepping- 

 stones to a more complete knowledge of the fauna. 



Of the districts to the southward, i.e., between 64° 30' 

 N. lat. and 60° N. lat., it is only necessary here to mention 

 that the western portions, e.g., the districts of Onega and 

 Ladoga and the Olonetz Government, have been lately 

 most carefully worked, and in the spring of this year we 

 may hope to receive the reports of the work done there 

 in 1875 and 1876. 



Further eastward, through the vast Government of 

 Vologda, there remains much unexplored ground, even 

 to the Ural ; and the upper valley of the Petchora (in 

 Vologda) and Northern Perm still require thorough 

 investigation. 



