30 Mr. H. Seebohm on the 



It appears to be impossible to construct a diagnosis of the 

 Passeres founded solely on osteological characters. All the 

 Passeres are segithognathous, but other birds, obviously not 

 Passerine, are also segithognathous. Most of the Passeres 

 have only one notch on each side of the posterior margin of 

 the sternum ; but some Passeres have two, and many birds 

 not at all Passerine have only one. In most Passeres the 

 outer episternal process or manubrium is well developed and 

 forked, but in some Passeres it is not forked, and in some 

 birds not Passerine it is forked. It seems therefore to be 

 necessary to call in some other characters, not osteological, 

 to complete the diagnosis. 



The deep plantar tendons are the muscles which, when 

 contracted, close the foot, and enable the bird to grasp its 

 perch or seize its prey. The different ways in which these 

 plantars are arranged afford characters which appear to be 

 of some value in the classification of birds. They run down 

 the back of the tarsus, sometimes side by side, but generally 

 crossing each other about the middle of that bone. The 

 inner and, when they cross, always the front plantar, is 

 named the flexor perforans digitorum ; the outer and, when 

 they cross, always the hind plantar, is named the flexor longus 

 hallucis ; but for the sake of brevity we may call the former 

 the front plantar, because it generally moves the front toes, 

 and the latter the hind plantar, because it generally closes 

 the hind toe. The most common arrangement of the plan- 

 tars is that found in the Common Fowl, and may therefore 

 be called the Galline arrangement. In this bird, when the 

 front plantar reaches the base of the tarsus it splits into 

 three tendons, one of which leads to each of the three front 

 toes. The hind plantar leads to the hind toe, but where it 

 crosses the front plantar it sends down a branch (called the 

 vinculum) to the front plantar, apparently to utilize its 

 superfluous strength, which would otherwise be wasted on 

 so feeble an organ as the hind toe of the Common Fowl and 

 other similarly formed birds. The size of the vinculum varies 

 according to the feebleness of the hallux. Where the hallux 

 is absent or very small the vinculum absorbs the whole of 



