V. 



The Bird's Foot. 



I. — By Frederic A. Lucas. 



I TRUST that the author of the note on the bird's foot, Natural 

 Science for July, page lo, will not consider me " a captious 

 critic " for saying that the statement that " in the great majority of 

 birds. . . . the tendon of the flexor of the great toe is connected 

 by a tendinous slip with the common deep tendon of the other toes" 

 may be a little misleading. 



Regarding the groups of birds in a general way, the statement 

 is true, but so far as mere numbers go, the Passeres and Kumming- 

 birds, which are schizopelmous {i.e., with the tendon to the great 

 toe unconnected with the common deep tendon), probably contain a 

 majority of species. 



Now in regard to the presence of the flexor longus hallucis in 

 three-toed birds, it seems to me that we can bring additional 

 evidence to sustain the proposition that it remains not as a mere 

 rudiment, but because it is functional. In certain lizards — possibly 

 in the majority, or even all — the long flexors of the foot unite 

 beneath the ankle and are worked by a single muscle ; and did we 

 know of any bird in which there was no separate muscle for the 

 ilexor longus hallucis, this bird would be considered as presenting 

 the primitive arrangement of the tendons. 



In the common Chimney Swift of North America (Chatum 

 J>elasgia) we have a comparatively simple condition of affairs. The 

 deep tendons are united for a considerable distance, and the tendons 

 to III, 2, and IV, 3,^ arise from a common slip. There is another 

 tendon to II, i, the total number of separate long tendons thus 

 being four. I, i, is worked by a separate muscle and tendon arising 

 from the upper inner portion of thetarso-metatarsus, this being present 

 also in other Swifts, in Humming-birds, and in such Passeres as I 

 have dissected. 



In another and more typical Swift, Micropus mclanoleucus, there are 

 rseparate tendons to II, 2, III, 2, and IV, 2, the deep flexors being, as 

 -before, firmly united. In Trochilus we have a somewhat intermediate 



' Roman numerals represent digits ; Arabic, phalanges. 



