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Trowbridge — Interlocking of Emarginate 



This paper contains the following sections : 



I. Emarginate primaries, their form and inter-relation. 

 II. Observations made at New Haven, Conn., in 1891, showing 

 the interlocking of the primaries in certain species. 



III. Observations made at New Haven, Conn., and at Paterson, 

 N. J., in 1904-5. 



IV. Measurements of the notches in the emarginate webs, 

 showing how long the primaries were interlocked. 



V. Species which have emarginate primaries. 

 VI. Three well-defined types of flight in Raptores. 

 VIT. Function of interlocked primaries in flight. 

 VIII. The wear of the primaries as shown by the microscope. 

 IX. Summary and Conclusions. 



I. Emarginate Primaries, their Form and Inter-relation. 



The number of primary feathers of the wing that are emar- 

 ginate in different species is often used as one of the means of 

 identification in standard works on ornithology. The emar- 

 ginate shape of these feathers is natural and not produced by 

 wear, as is well known. It is very marked in eagles and 

 hawks and other birds of prey. In some species, six out of ten 

 primaries are deeply emarginate on the posterior web. 



A complete set of emarginate primaries of a common hawk 

 (Buteo lineatus) are shown in fig. 1. In this species the first 



