I X T R D L C T 1 X 



The Swallows appear to us to be sucli a well-marked and isolated Family of Passeres, 

 that, in tlie absence of any detailed account of their anatomy and general structure, 

 which, so far as we know, lias not been attempted, there remains little for us to say. By 

 Linnjeus and the earlier Avriters the Swallows ivere united with the Swifts and all were 

 placed in tlie genus Uirundo. Then in course of time they were recognized as a separate 

 Family, but they were not allowed to escape from their ancient entanglement, and, side by 

 side with the Swifts, they flourished as members of the wide-gaping birds, or "Fissirostres." 

 When the " rostral " system became somewhat exploded, they were ruthlessly separated 

 from their former companions, until now, in due course of re-action, they seem to be 

 recognized as Passerine Birds of a somewhat Cypseline tendency, or perhaps, one might 

 more truly say, the Swifts are Cypseline Birds with a Ilirundinine tendency. For 

 the nine years in wliicb this book has been in publication, we entertained the hope 

 that some competent Anatomist would enact such a comparison of the characters of 

 the two Families that we should have been able to summarize the results, and tell our 

 readers exactly how the Swallows may be differentiated from the Swifts in e\ery jjoint 

 of structure. In default of this much-needed exhaustive essay from our more expert 

 brethren, we venture to define the characters of the Uinindinkhc as follows: — 



A. Passerine Birds with nine primary quills. 



B. Spinal feather-tract bifiu'cated. 



C. A single moult in the year, executed, so far as we know from the migralury 



species, during their residence in the winter home *. 



No Passerine Birds, we believe, present this triple combinaliou of charaelers, l)ut 

 further information is, of course, desirable. 



In 18i)l, in the 'Catalogue of Osteological Specimens in ihf .Museum df llif Jtnyal 

 College of Surgeons,' we placed the llirniulljuiht' at the ciul of the series of " Passeres 



* It is extremely importiint to know whellier the spe^'ies which arc resident in restrieted areas iolluw the rule 

 of the lui'^rator}- species, and have but u single moult. 



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