Contributions to Bird-Anatomy and Classification. 39 



this mentioned combination *, and in two of these the excep- 

 tion is caused by the entire absence of the oil-gland (in the 

 Otididae and the Struthiones) . Of the remaining seven, in 

 which the C£Eca and a tufted oil-gland are not correlated, I find, 

 by tabulation, that four always have the ambiens muscle de- 

 veloped, w^hilst the remaining three have it present in at least 

 some of their members. Of these latter, moreover, two have 

 the accessory femoro-caudal (B) always present ; so that it is 

 only certain Parrots which have a formula like that of any 

 anomalogonatous bird (for it must be remembered that in 

 several Parrots the ambiens muscle is present). This fact 

 will be made clearer by the accompanying table, containing 

 the names of the three main groups of the Anomalogonatse, 



a 

 < 





Anomalogonato!. 



Oypseliformes 



Passeriformes 



Piciformes 



Exceptional Homaloyonatce. 



MegapodidfB 



Thalassidrominae 



Musopliagidse 



Psittacidas 



Columbidse 



Cuculidse 



Cathartidse , 



Other Homalogonat(d 



+ 

 + 

 + 

 + 

 ± 

 + 

 + 



+ 

 + 

 + 



+ 

 ± 



+ 



±t 



+ 

 + 

 + 

 + 



+ 



+ 



± 



+ 



+ 



* One or two genera in various families, as e, g. Cancroma, have also 

 lost the oil-gland tuft. As, however, aU the allied genera retain it, these 

 slight exceptions in no way invalidate Prof. Garrod's argument. 



t In Momotus the tuft is absent. 



