296 BIRDS OF THE REPUBLIC OF PANAMA — PART 3 



with that species throughout most of its range. The two, though in 

 general similar, on close scrutiny differ definitely in important details. 

 The distinction was noted early by Kaup, when in 1852 he separated 

 Erator as a subgenus in his broader group Psaris, which included an 

 assemblage of the smaller cotingas. Ridgway, in his Birds of North 

 and Middle America (U.S. Nat. Mus., Bull. 50, pt. 4, 1907, pp. 777 

 in key, 860-861) noted the "close superficial resemblance to Tityra" 

 and gave a clear outline of the external dififerences for their distinc- 

 tion. In Erator these are the normal feathering of the side of the head 

 around the eye and the lores, the relatively flatter, longer bill, in 

 which the gonys is decidedly longer than the mandibular rami, and 

 the form and size of the hook at the end of the maxilla. The outer 

 side of the tarsus also has a row of large, more or less square scutes. 



In Tityra, a broad space surrounding the eye and the lores is bare 

 except for a few scattered, hairlike bristles ; the bill is stout and 

 arched, with a strong hook at the tip of the maxilla, and the 

 mandibular rami are as long as the gonys. The outer side of the 

 tarsus has small hexagonal scutes, similar to those on its back. 



Hellmayr (Cat. Birds Amer., pt. 6, 1929, p. 204) apparently did 

 not check these details as he united the two groups under the name 

 Tityra, remarking only that he did not "see any practical advantage 

 in subdividing this well-defined group." The dififerences are readily 

 apparent. It may be noted in addition that in a series of skulls of 

 Tityra, represented by T. semifasciata and T. cayana, the base sup- 

 porting the external nares is ossified as a circlet of bone attached 

 to the premaxilla at the front of the nasal opening. In addition, 

 the anterior end of the frontal is considerably expanded at the front 

 of the orbit, and the lachrimal is enlarged. In Erator inquisitor the 

 nasal capsule is not ossified, except in the central septum, and the 

 lachrimal is slender. The two species groups, though dififering so 

 definitely in structure, have thus an interesting superficial similarity 

 in appearance. In Venezuela both species have the native name 

 bacaco. 



As recognized currently, Erator inquisitor ranges from southern 

 Mexico south through Central America (except El Salvador) and 

 northern South America to western Ecuador, eastern Bolivia, north- 

 ern Argentina, Paraguay, and southeastern Brazil. Two of the six 

 geographic races recognized are found in Panama. 



It may be noted that the three more southern geographic forms, 

 typical inquisitor, pelselni, and erythrogenys in the adult male have 

 the side of the head completely black. In the other three, huckleyi, 



