xn INTEGDUCTIOX. 



Normales," and in our 'Classification of Birds' Ave fiirther separated tlieni from the 

 ordinary Percliing Birds or Passerifornies (RevieAV Classif. B. p. 80, pi. xi.), placing- 

 them at the end of the series, and illustrating their position in the natural system as 

 Passerine Birds without oiuj oery close ullies. We have seen no reason to depart from 

 tliis conclusion, and until the study of the anatomy, style of moult, and other features 





in It tvt- 



'if YMm % 

 J) Mj\\m ^ 



■■'tnOHAL TRACT . 



Dorsal view of Htnindo mstica, to show the ptenlosis, with the spinal feather-tract forked on the lower back. 

 (From the 'Catalogue of Osteological Specimens in the lloyal College of Surgeons,' by the kind permission of 

 the President and Council.) 



of certain Muscicapiue genera — such as Artoviylas and SemicheUdoii — tend to hridge 

 the gap, "\ve shall continue to regard the Hirmiclinidce as ))eculiar Passerine Birds, 

 standing well apart from the rest of the existing Passeriformes. 



Tlie SlmmdlniclcB were divided by us in 1870 into two Subfamilies — Sirundinince 

 (True Swallows) and PscdidojiroGninai (Pv,ough- winged Swallows). 



The Swallows are represented by twelve genera, which might almost he characterized 

 by the peculiarities of their nesting-habits as follows : — 



^xxUixmilj 1. niBUNDININ.^. 

 Genus 1. CIIELIDON. 



Nest. Of mud-nodules, entirely constructed by the birds themselves, lined with grass, 

 feathers, &c., and fixed against the wall of a house or cliff. 



Eggs. Pure white. 



Genus 2. COTILE. 



JSlest. A ragged structure of grass, &c., lined with feathers, placed in the hole of a 

 bank. 



Eggs. Pure Avhite. 



