THE PIGEON. 211 



133. On the dorsal surface of the conical posterior extremity of the 

 trunk is a small papilla on the apex of which opens the duct of the 

 uropygial or oil-gland ( 296, p. 247). 



134. The division of the fore-limb or wing into a 

 proximal portion, the brachium or upper arm, a middle 

 portion, the antibrachium or fore-arm, and a distal portion, 

 the manus or hand, the three divisions being bent upon 

 one another when at rest in the form of a Z : the absence of 

 distinct digits, except in the case of the pollex or thumb, 

 which forms a small projection on the pre-axial ( 94) border 

 of the manus at its proximal end. 



135. The alar membrane, a fold of skin, extending 

 between the proximal end of the fore-arm and that of the 

 hand on the pre-axial side. 



136. The division of the hind-limb into a proximal 

 portion, the thigh or femur, a middle portion, the shank or 

 crus, and a distal division, the foot or pes ; the latter 

 consists of a proxirnai stem, the tarso-metatarsus, and of 

 four digits, the first (pre-axial, in) of which is directed 

 backwards, and all of which terminate in strong claws. 



137. The arrangement of the feathers on the neck and 

 trunk : they are not continuous, but form a number of 

 feather-tracts or pterylae, separated by featherless 

 spaces or apteria : the former being indicated in the 

 plucked bird by the scars left by the removal of the 

 feathers. 1 Along the dorsal surface runs the spinal tract, 

 the cervical portion of which is particularly well marked, 



1 The pterylosis, or feather arrangement, is better made out in the 

 sparrow than in the pigeon, as in the latter the feathrr tracts tend 

 to run together : in the sparrow, on the contrary, the spinal iract is 

 almost linear, broadening out only in the lumbar region ; the ventral 

 tract consists of two very narrow bands separated by an inferior space 

 occupying nearly the whole of the pectoral region ; the lateral spaces are 

 also very large. 



P 2 



