On the Groups of the Falconiclce. 321 



entirely separated ; and the tarsi are covered with strong, promi- 

 nent, and thickly reticulated scales.* The well-known Osprey of 

 our coasts, F. haliceetus, Linn., is the type of the genus to which 

 the valuable researches of Dr. Horsfield, in Java, have added a 

 second species, P. Ichthyceetus-A In this species, however, which 

 agrees with Pandion in the more essential characters, we find a 

 strong approximation to the following genus Haliceetus. Its bill 

 is more compressed than that of Pandion, its acrotarsia are scu- 

 tellated, and the fourth quill feather, as in Haliceetus, is the long- 

 est. It thus stands osculaut between the two groups. 



The last group of the Fishing Eagles is comprised in the 

 genus 



Haliceetus, Sav. 



which differs from Pandion in the structure of the nails, and the 

 more compressed culmen of the bill. The tarsi also differ in 

 having the acrotarsia scutellated ; they are also feathered half-way 

 below the knee. The toes, like those of the last are entirely se- 

 parated, and the outward versatile. Our common Sea Eagle, F. 

 leucocephulus, Linn., affords the type of the genus, to which M. 

 Cuvier has added F. Pondicerianus, Gmel. F. blagrus, F. vocifer, 

 and F.vulturinus of M. Daudin. Some species lately described, 



* The scales that cover the acrotarsium will be found to form a very distin- 

 guishing character among the Falconidce. In some groups the acrotarsia are 

 scutellated, or covered with transverse and nearly quadrate scales, each of which 

 extends entirely across them. In others they are reticulated or covered with 

 smaller scales, chiefly hexagonal, that run into each other in a kind of network, 

 leaving two or more on a line in front. I take this opportunity of stating that 

 in the present sketch I pass overmany other characters of some importance,that 

 may be referred to in illustrating these groups, such as the structure of the acro- 

 jpodium, pelma, acrodactylum, hypodactylum, &c. with many others. The diffi- 

 culty of procuring subjects for examination, and in sufficiently good condition 

 to enable me to judge of these minuter characters, prevents me at present from 

 referring to them at all, when I can not refer with precision. I hope the future 

 observation of naturalists who have the opportunity of accurate examination, 

 may be directed to these and similar characteristick marks of distinction. They 

 will be found, I make no doubt, of singular service in illustrating the groups of 

 Ornithology. 



T Horsf. Linn. Transactions, xiii. 



Vol,. I. Y 



