320 STRUCTURE AND CLASSIFICATION OF BIRDS 



As to the pterylosis, there is a long spinal apterion, which 

 begins on a level with the shoulder joint and reaches to a 

 little beyond the level of the hip joint. Thence the two 

 dorsal tracts are continued on as a single tract to the 

 feathered oil gland. On the neck below there is no apterion ; 

 the two tracts then divide, leaving a bare interclavicular 

 space ; they divide again on a level with the anterior end of 

 the carina sterni into a lateral thick patch and a median 

 thinner one ; this latter swells out in its course and then 

 again dwindles, being continued to the cloacal aperture by a 

 few scattered feathers. 



The pectoralis I. (at any rate in T. Sykesi) is two-layered. 

 The tensor patagii brevis tendon gives off a wristward slip, 

 but there is no patagial fan. 



There is no biceps slip, but the expansor secundariorum 

 is present (? as to both these structures in Pedionomus}. 

 The muscle formula of the leg is the complete one ABXY + 

 in Pedionomus ; Turnix has lost the accessory femoro-caudal 

 for the most part not, however, in T. Kleinschmidti, where 

 it is present. It is remarkable that in Pedionomus it is not 

 B but A which is on the wane. 



Both carotids are present in Pedionomus, only the left 

 in Turnix ; but in Pedionomus the left is the weaker and 

 not the right, as might perhaps have been suspected. 



The alimentary canal has no crop, ' but the upper half 

 of the oesophagus is very dilatable ' (in Pedionomus). The 

 ccBca are well developed ; the liver in both genera is split 

 into three nearly equisized lobes. The gall bladder is 

 present. 



The syrinx (of Turnix lepurana) is not at all gallinaceous 

 in its characters. The tracheal rings are weak and carti- 

 laginous. The intrinsic muscles are thick and originate in 

 close contact from the anterior face of the trachea ; they are 

 inserted some way down the bronchi on to the opposite face 

 of the tubes. In Hemipodius tacliijdromus the windpipe is 

 very soft, and is much dilated in front of the origin of the 

 intrinsic muscles, which, as in the last species, are large. 



Our knowledge of the osteology of the Heinipodes is 



