PANBIONID.'E. 



313 



always 11 primaries. The Jlexor longus Jiallucis leads to the hallux 

 and the Jlexor 2'>erforans dir/itorum to the other three digits, but 

 the two tendons are united by a fibrous vinculum. The ambiens 

 muscle and the femoro-caudal are present, the accessory femoro- 

 caudal, semitendinosus, and accessory semitendinosus are absent. 

 The posterior border of the sternum is not notched, but there is 

 sometimes a foramen on each side within the border. There are 

 no basipterygoid processes, and the palate is desmognathous. 

 Both carotids are present, and there are eseca of the intestine. 

 The nest is generally of sticks, and is placed on a tree or on 

 rocks. The young are hatched helpless and covered with down ; 

 they remain in the nest for a considerable time. The female 

 throughout the order is almost always larger than the male. 



Accipitrine birds may be thus divided into three families : — 



a. No aftershaft to contour-feathers; outer toe 



reversible Pandionidae,p.313. 



b. An aftershaft present; outer toe not or very 



slightly reversible. 

 a'. Crown of head naked or covered with down. Vultundae, p. 315. 

 b'. Crown of head feathered Falconidae, p. 327. 



Family PANDIONID^. 



The Osprey differs from all other Accipitrine birds in having the 

 outer toe reversible, and in having no aftershaft to the feathers. 



The characters of the tibia and tarsus (tarso-metatarsus and 

 tibio-tarsus) have been shown by Lydekker (Cat.Foss. BirdsB. M. 

 p. 18) to be Owl-like, as are the other distinctive peculiarities 

 iiist mentioned, and it is unquestionable that the Osprey forms a 

 link between Accipitrine birds and Owls, and that it differs from 

 the Falconidoi much more than the Vultures do. 



Genus PANDION. 



Bill moderate, with the tip produced and much hooked ; festoon 

 variable; nostrils small, narrow, oblique. Wings long and 

 pointed ; third quill longest, extending beyond the end of the tail, 

 which is nearly even. Tarsus short, stout, reticulated, without 

 scutation ; toes with scutse above only near the ends, covered with 

 prickly scales beneath; claws rounded beneath, much curved, 

 subequal in size. 



A single species. 



