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 proximal 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 pterylse, 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, 



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

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

 to run together : in the sparrow, on the contrary, the spinal tract 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 



