PASSERES. 



3 



be inferred, as is verified by dissection, that the tendon of the 

 flexor longns liallucis crosses its companion superficially on its way 

 from the ankle to its insertion in the hallux. 



" Just before, or just at the commencement of, the sole of the 

 bird's foot (near the joint between the metatarsus and the 

 phalanges) these two tendons generally split up to supply the 

 toes." 



The manner in which these tendons serve the toes and their 

 relation to each other, when combined with other characters, are 

 of the greatest service in diagnosing the various orders of birds. 



The deep plantar tendons are said to be passerine when the 

 flexor perforans digitorum serves the three front toes and the 

 flexor longus liallucis serves the hind toe, both tendons being 

 perfectly disconnected in such a manner that the hind toe is 

 separately movable from the front toes. This formation is shown 

 in the accompanying sketch : 



hallux 



ankle. 



. ... tarso-metatarsus. 



digits... 



Sketch showing the arrangement of the deep plantar tendons in a 

 passerine bird. (From P. Z. S. 1875, p. 347.) 



The determination of the character of the deep plantar tendons 

 in a freshly-killed bird is very easy. In a dried state the tarsus 

 and toes must be macerated in water until soft, when the tendons 

 can be dissected without difficulty. 



B2 



