1875. ] PLANTAR TENDONS IN BIRDS. 347 
special characters of that muscle only, it being distributed to three 
toes, whilst the flexor perforans digitorum only supplies one. 
The birds with seansorial feet thus fall into two divisions, accord- 
ing to the arrangement of their plantar tendons, these being normal 
in the Psittaciand Cuculide, whilst they are extremely peculiar in the 
Picida, Ramphastide, Capitonide, and Galbulide. In my paper 
on the Classification of Birds*, the presence or absence of the am- 
biens muscle made me feel justified in placing the Psit¢act and Cucu- 
lide among my Homatoconar4, at the same time that the Pici, 
Ramphastide, Capitonide and Galbulide are arranged among the 
ANOMALOGONAT#. These new observations are therefore strongly 
in favour of the naturalness of the classification proposed. 
There is only one other point to be considered on the present 
occasion, as far as this question is concerned. It is the distribution 
of these tendons in birds which do not possess the hallux, or in which 
Fig. 9. 
—~| 
A typical Passerine Foot. 
there is no long flexor tendon to that digit when it is present. In 
all these cases both the flexor longus hallucis and the flewor perforans 
digitorum muscles are present and well developed, only they blend 
completely opposite the upper part of the tarso-metatarse to form 
a single common tendon to be distributed, on its splitting up, to the 
anterior toes—to the two of Struthio, the three of Rhea, Otis, 
* P. Z.S. 1873, p. 626, and 1874, p. 111 ef seq. 
