THESES. O. HERMAN. 



nation, the masses disperse, according to the topographical situation of 

 these places. 



20. Many observers took the branching-off of the tribes from the 

 main direction for the original direction of Migration, thus causing flagr- 

 ant contradiction. 



21. The non-observation of these branchings-off, their conception 

 as original directions, and finally their being ideally lengthened in enter- 

 ing them on the maps, led to diametrically opposed ideas in regard to 

 the cartographical routes of migration or their direction. 



22. Tribes keep together in joining a body of migrants. 



23. Upon the territorial range of the tribes is based the subspecific 

 difference, as far as recognizable within the limits of differentiation. 



Concrete cases. 



24. The migratory conduct of Anthus cervinus („Aquila" VI) proves 

 the migration in tribes, as well as the tribal distribution in the hiber- 

 nating region. Southerly range from Borneo to Algeria, northerly from 

 Kamtchatka to Western-Finmark. Eastern and western form of the 

 species is subspecifically distinguishable. 



25. The Swallow (Hirundo rustica) settles in Europe, reckoned from 

 Gibraltar to Lulea, in 105 days. 



Arrival in Gibraltar lat. 30" ION. 13. of February.* 



Arrival in Lulea lat. 65" N. — 29. of May.** 



The young swallows in Gibraltar are already fledged, when the 

 old ones arrive at LuleA. This proves indisputably that settling does 

 not depend on the power of flight. 



26 Howard L. Irby (ibid.) observed at that the time when the Swal- 

 lows were already settled in Gibraltar, during 70 days — from the 13th 

 of February to the 24th of April others passed northward, no doubt 



Irby, Howard L: „The Ornitholof^y of tlie Straits of Gibraltar" London 1S95. 

 Nordlinder in litt. Series. 



ei 21 iZ9 



