ANOMALOGONATJE 171 



There are other peculiarities that unite these birds, which 

 will be found mentioned on p. 183. 



The third group, containing the hornbills and hoopoos, 

 may be thus defined : — 



Group C. — Oil gland feathered ; fifth remex present. 

 Muscle formula, AXY. No expansor secundariorum. Caeca 

 absent. Skull desmognathous. 



The colies are the only birds among the Anomalogonatse 

 besides the Caprimulgidse which possess the biceps slip ; there 

 is a rudiment of this structure in Bucorvus. 



The remaining families are treated of separately and need 

 not be defined here. 



This arrangement, nearly coincident with that of Gadow, 

 is widely different from that of G-aeeod and Foebes. The 

 former divided the birds (excl. Striges) into the three groups 

 of Piciformes, Passeriformes, and Cypseliformes. They were 

 thus defined : — 



Piciformes. — Oil gland tufted ; caeca absent ; external 

 branch of pectoral tract given off at commencement of breast. 

 Muscle formula, (A)XY. Picidae, Capitonidae, Upupidae, 

 Bucerotidse, Goliidae, Alcedinidae, Momotidae. 



Passeriformes. — Oil gland nude ; caeca present ; pectoral 

 tract simple or with external branch given off beyond middle 

 of breast. Muscle formula, AX (Y). Passeres, Bucconidae (?) , 

 Galbulidae, Goraciidae, Meropidse, Trogonidae. 



Cypseliformes.— ^Oil gland nude ; caeca absent. Muscle 

 formula, A. 



To these Foebes added a fourth group Todiformes, on 

 account of its having at once caeca and a tufted oil gland. 

 This latter group was regarded by him as most nearly repre- 

 senting the ancestral anomalogonatous bird. 



