70 Transactions. —Zoology. 
The shaft at one-third of its total length above its distal end is nearly 
round in a transverse section, a feature it has in common with Circus, 
whereas the shaft of Aquila is more subelliptic. 
The articular head forms a more distinct tuberosity than in Aquila, which 
is also observable in Circus; a broad groove dividing it from the ulnar crest, 
which advances considerably over the pneumatic foramen. 
The radical crest being partly broken off, its whole extent cannot be 
ascertained. The ridge forming the boundary of the large depression for the 
insertion of the pectoralis major is well marked. 
The articular convexities of the distal extremity are also of considerable 
size, and well carved out ; the pits for the attachment of the muscles are large 
and deep, all tending to prove that Harpagornis possessed considerable power 
of flight. 
ULNA. 
Harpagornis moorei. 
This bone has the following dimensions :— 
Inches. 
Total length  ... ges d 5a 19:06 
Circumference at its рна end . ы MUN TO 
Cireumference at its distal end E d SUP D 
Circumference of shaft where thinnest h UIT 
In comparing its total length with the dite pou TM in Aquila 
audax, as given in the table of measurements, it will be seen that it is only 
0-68 inch longer, but that it is distinguished from it by its considerable 
thickness and the greater expansion of both articular ends. This is most 
conspieuous when examining the proximal surface, but, considering the great 
breadth of the distal end of the humerus, quite a natural consequence. 
The anconal side of the'shaft is rather flatter than in Aquila, so that the 
bone does not exhibit quite such a great curve as the latter. 
The quill knobs are obliterated. $ 
Harpagornis assimilis. Pl. VIII., Figs. З and 4. 
Inches. 
"Total length 2i 9:35 
Circumference of ойша Ee sei eas 24 0 0790 
Circumference of distal end 5 Ves vci Wd 
Cireumference of shaft where dhinnest с 1:48 
The pachydermal character of the genus wider sisi detto) when 
compared with Aquila audax, is well exhibited in this ulna, because, being 
actually shorter than the corresponding bone in the Australian species, it is 
much shorter in all its proportions. 
The ulna of this species being better preserved than that of Harpagornis 
moorei has been figured by preference. The two rows of quill knobs, and 
