178 EAR 
noticed here a small group of Eagles, characterized by their long 
legs, forming the genus Nisueius, of which one species, NV. fasciatus 
or bonellii, is found in Europe. The Osprey (Pandion), though 
placed by many among the Aquiline, certainly does not belong to 
that subfamily. 
EAR. 'The whole auditory apparatus is divided into the outer, 
middle, and inner ear. 
The outer ear or “auditory meatus” is a short, membranous, and 
sometimes partly cartilaginous tube. The outer opening is generally 
covered by feathers, and rarely naked as in Vultures and Ostriches. 
The feathers which surround the ear are often more or less reduced, 
and occasionally assume the shape of bristles. ‘There is no external 
ear or “concha auris,” but a more or less prominent fold projects 
from the outer margin into the meatus, and seems to be used as 
a sort of imperfect valve, especially since it possesses several little 
muscles. Such a valvular fold attains its largest development in 
Owls. Many of these birds present the peculiar anomaly of 
having the outer ears very asymmetrically developed, an asym- 
metry which often affects also the whole of the temporal region 
together with the squamosal, quadrate, and neighbouring bones, 
so that the whole skull assumes a lop-sided shape. Collett 
(Christiania Videnskabs. Forhandl. 1881, No. 3, pp. 1-38, pls. i.-ili.) 
has examined this point in all the North-European species of Owl. 
According to him there are three different formations: 1. Skull 
and auditory meatus symmetrical, ear-valve absent: Surnia 
funerea, Glaucidium passerinum, Nyctea scandiaca, Bubo ignavus. 
2. Skull symmetrical, meatus asymmetrical, ear-valve present: Asio 
accipitrinus, A. otus, Strix aluco. 3. Skull and meatus asym- 
metrical, ear-valve present: Strix uralensis, 8. lapponica, and 
Nyctala tengmalmi. Of other, not North-European, Owls, Aluco 
flammeus belongs to the first group.! 
Another peculiar modification is exhibited by the CAPERCALLY. 
It is well known that the cock for several seconds towards the end 
of his rutting ecstasy is completely deaf to any external sounds. 
This deafness is produced by an erectile fold of the posterior wall 
of the auditory meatus; this fold or flap becomes turgid with 
blood during the excitement of the bird, and seems moreover to 
be assisted in pressing upon the opposite margin of the quadrate 
bone, and in thus effectively closing the ear-passage, by the action 
of the digastric or depressor muscle of the mandible which is 
always widely opened during this stage. The harsh and loud 
sounds emitted by the cock, and the blocked ear-passage render 
him absolutely indifferent to any other sounds. (See Graff and 
1 A large number of figures of North-American species in illustration of this 
point is given by Ridgway (North American Birds, iii. pp. 97-102). 
— 
BD. oe ited & 
