Falconid^.] osteologia avium. [Milvim. 



Circus, Lacep. 



Cyaneus, Linn. 

 Type of Circinse. 



Cranium similar to Falco peregrinus, but with the frontal bones not so broad between 

 the orbits. Lacrymals large, extending more outwards than in Falco, and further 

 lengthened by a small epilacrymal process articulated to their extremities. The orbital 

 septum perforated with a central foramen. Nasal orifices triangular. Palatine bones with 

 the hinder angles nearly square, and the dependent keel on their internal edges narrow. 



Sternum small, very slightly convex, narrow anteriorly ; keel not so deep as in Falco ; 

 inferior edge arched, not produced to the posterior margin of the sternum, receding 

 anteriorly. Posterior margin of the sternum perforated by two small foramina. 



Pelvis with the iliac bones much overhanging the bones of the ischium. 



Metatarsus with the calcaneal process well developed, but with no ridge carried 

 downwards from it ; the ento- and exo-metatarsal elements very much flattened, and 

 folding backwards, while the edge of the mesometatarsal projects forwards, forming an 

 anterior ridge. 



The remainder of the skeleton is very similar to Falco. 



Measurements. 



Tenths. 

 Breadth of posterior margin of sternum 17 

 Breadth of anterior margin of sternum 14 



Depth of keel , . . 5^ 



Length of head 30 



Breadth of head 17 



Length of pelvis 30 



Breadth of pelvis 15 



Tenths. 



Length of humerus 41 



Length of ulna 48 



Length of radius 47 



Length of metacarpus 24 



Length of femur 28| 



Length of tibia 40 



Length of metatarsus 30 



Length of sternum 26 



Illustrations. 

 Sternum, Plate III. fig. 4. | Metatarsus, Plate II. fig. 4. 



Circus, Lacep. 



iEruginosus, Linn. 



I have the sternum only of this bird, which does not differ in form from that of Circus 

 cyaneus, except in being destitute of foramina on its posterior margin. 



Subfam. 3. Milvin^e. 

 Milvus, Cuv. 



Kegalis, Linn. 



Type of Milvinee. 



Cranium similar to that of Falco peregrinus, but not so strong, and longer in pro- 



7 



