I06 NEW YORK STATE MUSEUM 



sive process to rest upon the coracoid and act as an abutment for the 

 clavicle of the same side. Passing to a coracoid, it is seen to be 

 somewhat short and stout, with very tuberous head. The foramen 

 which usually perforates the shaft from before backward, is very 

 large and elongated; or it may be represented by a long, shallow 

 notch ; or it may be entirely absent. The scapular process of a 

 coracoid is long, pointed, and curves upward and outward toward 

 the anterior aspect of the head of the bone. When the bones of this 

 girdle are articulated in situ, this process passes behind the clavicle 

 of the same side. 



Specimens in my collection of Falco sparverius show 

 that this process may not only meet the head of the coracoid or 

 rather a spicula of bone thrown downward and inward from it, 

 but fuse with this last, and thus create a bridge for the clavicular 

 limb to rest upon.^ 



No very marked characters, aside from the differences in size, dis- 

 tinguish the pectoral limb of Falco mexicanus from the 

 corresponding part of the skeleton in such a hawk as B u t e o 

 1 i n e a t u s ; albeit we do find a few good differential characters in 

 the skeleton of the pelvic extremity. Upon comparing them we find 

 the femora much alike, as well as the bones of the leg. though at 

 the distal end of the tibiotarsits the osseous spanlet for the tendons 

 is somewhat differently formed, though it agrees in character. 



The first real diff'erences we meet with are referable to the tarso- 

 metatarsus and skeleton of pes. In the Falco the hypotarsus oi the 

 tarsometatarsus consists of a small external process, and a far more 

 prominent internal one, which latter is directly extended down the 

 back of the shaft of the bone as a raised crest with expanded free 

 margin. This crest merges into the shaft at about its middle. With 

 the Buteo we have already shown its morphology above [see also 

 figure of the tarsometatarsus in Circus]. In the Falco the pair of 

 anteroposterior perforating foramina of the shaft are much larger 

 than they are usually seen to be. They pierce the shaft one upon 

 either side of the inner hypotarsial process or crest. Another good 

 character is seen in the position of the osseous tubercle for the in- 

 sertion of the tendon of the tibialis anticus muscle. It is situated 

 to the left of the center of the shaft in Falco mexicanus 

 and to the right of the center in Buteo 1 i n e a t u s . Eagles 

 also have it situated to the right of the center. The basal joint of 

 the second toe is relatively not nearly so much shortened in Falco 



' If this, the true fate of this scapular process of the coracoid, be compared with 

 what Huxley, Eidgway and Coues have written about it, it will be seen to be very 

 different. 



