76 On the Structure and Habits of the Elanus Melanopterus. [July 



Form. The female is 13 inches long, by 35 in expanse of wings, and 

 8| oz. in weight. The male is about 1 inch smaller, and seldom weighs 

 above 71 oz. Both have the same aspect. The following is a detail 

 of the dimensions of a male : — 



inches, parts. 



Tip bill to tip tail , 12 \ 



Bill, length, from gape 1 -J 



Bill, length, from brows . 0 J-| 



Bill, basal height 0 -fjt 



Bill, basal width 0 \\ 



Length of tail 5 § 



Expanse of wings 34 0 



Length of a closed wing 10 f 



Length of tarsus, to sole **. , .... 1 T \ 



Length of central toe c m -\ 1 T \ 



V exclu- / 



Length of inner fore toe ^ sive of > 0 -i-f 



Length of outer fore toe v. J 0 \~ 



Length of hind toe 0 T 9 ¥ 



Length of hind talon (straight) ... 0 \\ 



The bill, from the gape, is as long as the head, that is, actually long : 

 but from the brow it is more distinctly short : a peculiarity caused by 

 the width of the mouth and by the advanced position of the frontal 

 plumes. Both the bill and the head, from the naves to the occiput, 

 are distinguished by great breadth ; but the bill, before the nares, is 

 much compressed and feeble. The bill is slightly curved from the 

 base ; its hook is long and sharp ; its upper mandible has a conspicuous 

 accipitrine festoon ; and its lower one is rather abruptly truncated but 

 not notched. The cere is of mean size, and is nearly hid by soft curl- 

 ing hairs which radiate from the four angle of the eyes and clothe the 

 lores an d orbits : the nostrils are oval, longitudinal, lateral, with a 

 full and free membranous edge on the upper margin. The eye is 

 lavge and is furnished with a conspicuous salient opercule. The wings 

 are vevy ample, and usually exceed the tail by 1| inch. Next to their 

 length, their chief feature is the breadth and softness of the webs or 

 vanes of the feathers. The second quill is invariably the longest j 

 and the third is longer than the first, the former being about I, and 

 the latter f, of an inch less than the second. The primes exceed the 

 tertials by more than a third of the entire length of the formeV. The 



