Ridgway.] 82 [May 21, 



Genus Geranospiza Kaup. 



Ischnoceles Strickl., 1844. Type, Falco gracilis Tenim. (not Ischno- 



celis Burm., 1842). 

 Geranospiza Kaup, 1847. Same type. 

 Geranopus Kaup, 1851. Same type. 



Ch. Form very slender, the wings and tail very long, the head 

 small, bill weak, and tarsi extremely elongated and slender. Outer 

 toe very much shorter and weaker than the inner, and about equal in 

 length to the posterior, its claw disproportionately small and weak. 

 Tibio-tarsal joint flexible both backward and forward! Secondaries 

 much developed, reaching nearly to the end of the primaries, and 

 very broad. Bill much as in Nisus ; nostril obliquely horizontal, 

 oval. Tarsus about two and a half times as long as the middle toe, 

 with frontal and posterior series of broad transverse scutellse, these 

 often fused into continuous plates ; claws normal. Tibial feathers 

 short and close, not plume-like. Wing long, but the primaries not 

 much longer than the secondaries, the fourth to the sixth quills long- 

 est, the first shortest, and much bowed ; outer six with inner webs 

 sinuated. Tail long, nearly equal to the wing, rounded, the feathers 

 very broad. 



This remarkable genus is closely related to Polyboroides of South- 

 ern Africa, with which it agrees in certain characters which separate 

 them from all other Falconidce, and mark them as very specialized 

 members of the buteonine group. The excessive abbreviation of the 

 outer toe, as compared with the inner, is shared by Heteropus (type 

 H. malayensis Reinw.) an aquiline form belonging to the East Indian 

 reoion; but the singular flexibility of the tibio-tarsal joint is probably 

 found in no other genus, unless it may possibly exist in a less exag- 

 erated decree in Melhierax of Africa, or still less developed in Uru- 

 bitinga zonura of Tropical America. Mr. Gurney speaks at length, 

 in his " Descriptive Catalogue of the Raptorial Birds in the Norfolk 

 and Norwich Museum" (London, 1864) of this peculiar feature in 

 Polyboroides, and mentions Geranospiza as being nearly related in 

 general form and other features. Through the courtesy of Professor 

 Aoassiz and Mr. Allen, of the Museum of Comparative Zoology, ai 

 Cambridge, I have been permitted to examine an alcoholic, specimen 

 of G. cazndescens, and find that the singular feature above referred 

 to is just as well developed in Geranospiza, thus confirming the rela- 

 tionship hinted at by Mr. Gurney. 



