INTRODUCTION. 21 



the nape). The u rump" (or lower back) often includes the 

 upper tail-coverts, the " belly " the under tail-coverts, etc. 

 The " sides " invariably refer to those of the breast and belly. 



U. Measurements of both birds and eggs are made in 

 straight lines between two points. To measure the length of a 

 bird, lay it on its back, and make the tip of the bill (so far as 

 reasonable) , and the end of the longest tail-feather, touch the 

 ruler or paper on which they are laid ; then measure the distance 

 between these points. Measure (with compasses) the tarsus 

 in front, and the bill from the tip of the upper mandible to the 

 feathers actually or apparently belonging to the forehead. 15 

 The "depth" of a bill is its vertical width near the base, when 

 closed. Eggs may be measured by dividers, or by a ruler 

 with a slide. For accurate measurements a ruler marked deci- 

 mally (or even with hundredths) is best. -^ of an inch equals 

 about -06. 



V. Birds form a class of the Animal Kingdom. They are 

 composed of three (or more?) distinct subclasses; the Aves 

 Aerece, Insessores, or typical "perchers;" the Aves Terrestres, 

 Cursores, or gallinaceous birds and "waders;" and the Aves 

 Aquaticce, Natatores, or "swimmers." These are grouped into 

 several orders (such as the Raptores or "birds of prey"), 

 which are divided into families (as the Raptores into Strigi- 

 dce, Falconidce, etc., or the hawks, including eagles, the owls, 

 and vultures). The orders are sometimes more primarily di- 

 vided into suborders, and families into subfamilies. Thus the 

 Passeres consist of the Oscines or singing passerines, and the 



" There are other methods of making this measurement. 



