NATURAL SCIENCES OF PHILADELPHIA. 



479 



sometimes interrupted, transverse scutellre to the base. Web 

 between outer and middle toes well developed. Claws of normal 

 form, well curved, and exceedingly sharp. Wing short, much 

 rounded, and very concave beneath, the primaries much bowed 

 (as in Nisus) ; third to sixth quill longest ; first shortest ; outer 



Fitr. 6. 



M. rufieollia. \A nat. size. 



five or six with their inner webs slightly sinuated. Tail very 

 long (nearly equal to or exceeding the wing), much rounded, or 

 graduated. Feathers of the crown and occiput well developed, 

 sometimes 1 large and broad, capable of being erected into a broad, 

 depressed crest. 



This well-characterized and very remarkable genus comes 

 nearest Herpetotheres, with which it agrees closely in osteologi- 

 cal structure as well as in essential features of external form ; but 

 it differs in many important points throughout its 

 whole anatomy more especially in the develop- 

 ment of the nasal bones, which are much less com- 

 pletely ossified almost as little so as in the Buteo- 

 ninas. It presents analogies with Circus and the 

 Strigidas in the facial ruff, and with the latter in 

 the character of the inner webs of the primaries, 

 as well as in the dimorphic plumage of some of the species, and 

 with Nisus in general aspect and mode of life. The remarkable 



M. rufieollia. 



Notably in the smaller species. (See Fig. 2.) 



