212 ZOOTOMY. 



and bifurcated posteriorly : on the ventral surface is the 

 ventral tract, divided in the region of the trunk into two 

 lateral portions separated from one another by the median 

 inferior space : throughout the greater part of its extent 

 the ventral is separated from the spinal tract by the lateral 

 spaces, one on either side of the trunk and neck. 



138. The arrangement of the tail feathers : attached along 

 the posterior edge of the rump are twelve large rectrices 

 or tail quills, the position of which is indicated by well 

 marked scars in the plucked bird : the proximal ends of the 

 rectrices are covered both above and below by smaller 

 feathers, the tail coverts, attached to the upper and under 

 surface of the rump. 



139. The arrangement of the feathers on the wing: along 

 the post-axial edge of the antibrachium and manus is 

 attached a row of about twenty large remiges or wing 

 quills, of which those attached to the manus are the 

 primaries, those attached to the antibrachium the 

 secondaries : their position is clearly indicated in the 

 plucked bird by large scars. Both on the upper and under 

 surface of the wing the remiges are largely covered by the 

 upper and under wing coverts, which also form the entire 

 feathery covering of the upper arm : on the dorsal surface of 

 the latter the feathers are arranged in a well marked 

 humeral tract : the secondary upper wing coverts spring 

 from an alar tract. A special tuft of feathers springs 

 from the pollex, and constitutes the ala spuria or bastard 

 wing. 



140. The arrangement of the feathers on the leg : there is 

 a well defined femoral tract on the dorsal surface of the 

 thigh, and a weak crural tract on the shank. 



i4r. The absence of feathers on the pes, which is covered 

 instead by horny scales : these are especially large on the 



