368 



ZOOLOGY 



SECT. 



axis of the entire wing is at right angles to that of the trunk. On 

 the anterior or pre-axial border of the limb a fold of skin stretches 

 between the upper arm and the fore-arm ; this is the alar membrane 

 or pre-patagium (pr. ptgm.). A similar but much smaller fold 

 extends, post-axially, between the proximal portion of the upper 

 arm and the trunk ; this is the post-patagium (pt. ptgm.). 



In the hind-limb the short thigh is closely bound to the trunk, 

 not standing well out as in a Keptile, but directed downwards and 



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FIG. 1033. Columba livia. The entire animal from the left side with most of the feathers 

 removed. ad.dg.rmx. ad-digital remex ; al. sp. ala spuria ; an. anus ; au. ap. auditory 

 aperture ; cb. rmg. cubital remiges ; cr. cere ; dg. 1, 2, 3, digits of manus ; dg. 1', 2', ?', 4', 

 digits of pes ; hu.pt. humeral pteryla ; Iff. ligament of remiges ; md.dff.rmg. mid-digital 

 remiges ; na. nostril ; nct.m. nictitating membrane ; o.gl. oil-gland ; pr.dg.rmg. pre-digital 

 remiges ; pr.ptgm. pre-patagium ; pt.ptgm. post-patagium ; ret. mesial rectrix of right side ; 

 ret', sacs of left rectrices ; sp. pt. spinal pteryla ; ts.mtts. tarso-metatarsus ; v.apt. ventral 

 apterium. 



forwards ; the long shank extends from the knee downwards and 

 backwards ; and the foot is clearly divisible into a proximal portion, 

 the tarso-metatarsus (ts. mtts.), and four digits, of which one, the 

 hallux (dg. 1'), is directed backwards, the others, the 2nd, 3rd, and 

 4th of the typical foot, forwards. The entire hind-limb is in a plane 

 parallel with the sagittal plane of the trunk. 



