MA.CROCHIEES 227 



Macropteryx, however, Lucas ' has described the flexor 

 hallucis as going to the first digit only after giving off a vin- 

 cukim to the tendon of digit IV. As to the humming birds, 

 there has been some confusion. It appears, however, that 

 the flexor hallucis before going to digit I. gives off a slip to 

 flexor communis of digit II., and (a.ccording to Gadow ^) 

 III. and IV. also. 



Both swifts and humming birds have, as a rule, only one 

 carotid, the left. The following swifts have two carotids : 

 Ghatura rutila (right carotid larger), Cypseloides fumigatus. 

 In Micropus ( ? Fanyptila) melanoleuca Shufeldt has 

 described the left carotid (the only one present) as crossing 

 over to the right and being until the middle of the neck free 

 of the hypapophysial canal. 



The chief peculiarity of the vascular system concerns the 

 femoral vein. In Fanyptila melanoleuca and in Ghcetura 

 zonaris the femoral vein, instead of running deep of the 

 femoro-caudal muscle, comes to join the sciatic artery and 

 nerve immediately it has passed the obturator extemus 

 superficial to the femoro-caudal tendon ; Cypseloides fumi- 

 gatus is the only other swift which has been shown to be 

 characterised by this structural abnormality. 



The large size of the heart of the humming birds as 

 compared with that of the swifts is commented upon by 

 Shufeldt. 



The syrinx of the swifts is not in any way remarkable ; 

 it is tracheo-bronchial, with the usual pair of intrinsic and 

 extrinsic muscles. The former are attached (at any rate 

 in Chcetura caudacuta) to the first bronchial semi-ring. In 

 Cypseloides fumigatus, however, a swift which is in other 

 ways abnormal, there appear to be no intrinsic muscles. 



The humming birds, on the contrary, have an unusual 

 form of syrinx, which is remarkable in two ways. 



In the first place the trachea bifurcates very high up in 

 the neck, recalling the characteristics of Platalea rosea, (see 

 below). Each bronchus in Trochilus colubris (according 



' Ibis, 1895, p. 298. " Ibid. p. 299. 



a 2 



