8 Mr. W. P. Pycraft on the 



overlapping the toes. The inner edge of the large scute 

 runs along near the middle line of the inner side of the 

 shaft, while the outer edge extends as far as the middle 

 line of the planta; the space between the two edges is filled 

 up by a long plate extending the whole length of the planta 

 and inner side of the tarso-metatarsal shaft. The large 

 sheath covering the acrotarsium, when carefully examined, 

 is found to be formed by a fusion of four separate scutes, 

 traces of which can be distinctly seen. 



Text-fi<?. 4. 



Left foot of Zeledonia coronata, shewing the podotheca. Only the faintest 

 traces remain of the originally separate scales which compose the 

 main sheath of the acrotarsium. 



Discretion must be used in employing the fusion or non- 

 fusion of the scales of the acrotarsium as a character of 

 systematic value. Even in different species of the same 

 genus I find that great variation obtains. Age doubtless has 

 much to do with the matter, the traces of scutes, Avhere fusion 

 of an originally separate series has taken place, being often 

 visible only in young birds and absent in adults. But let 

 it be distinctly understood that I do not mean to decry the 

 value of the squamation of the leg as an aid in distinguish- 

 ing members of different Ci Families " of Passeres. There 

 it is often very useful. Thus, to take a case at random : 

 the squamation of the acrotarsium of the Sturnidse differs 



