XITI 



PHYLUM CHORDATA 



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which is widely distributed in the Pida'arctic and Oriental regions. 

 The following description refers especially to the common Dovecot 

 Pigeon. 



External Characters.— In the entire Bird (Fig. 1022) the 

 plump tiunk aj)pears to be contiinied insensibly into the small, 

 mobih^ head, with its rounded brain-case and prominent iMytk, 

 formed of upper and lower jaws covered by horny sheatlis. The 





md.cL^.rmo 



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Fig. 1022.— Columba livia. The entire animal from the left side with most of the feathers 

 removed. aii.d<i. mu . ad-digital remex ; al..ip. ala spuria ; an. anus; au.ap. a;iditory 

 aperture; cb.rnig. cubital remiges ; cr. cere; dff. 1, 2, 3, digits of manus ; dg. V , f , 3', W, 

 digits of pes ; hu. pt. humeral pteryla ; Ici. ligament of remiges ; md. dg. rmg. miil-digital 

 remiges ; na. nostril ; net. m. nictitating membrane ; o. gl. oil-gland ; 'j'l: dg. ring, pre-digital 

 remiges ; pr. ptgm. pi'e-patagium ; pt. ptgm. post-patagium ; ret. mesial rectrix of right side ; 

 ret' . &;\c& of left rectrices ; sp. p<. spinal pteryla; <«. i/i/^.s. tarso-metatarsus ; v. apt. ventral 

 apterium. 



head, neck, and trunk are invested in a close covering oi feathers, 

 all directed backwards and overlapping one another. Posteriorly 

 the trunk gives origin to a number of outstanding feathers which 

 constitute what is ordinarily called the tail. From the anterior 

 region of the trunk spring the iviitgs, also covered with feathers, 

 and, in the position of rest, folded against the sides of the body. 

 The legs spring from the hinder end of the trunk, but, owing to 



