Chap. I. 
RUDIMENTS. 
23 
whole external ear being permanently pressed back- 
wards. In many monkeys, which do not stand high in 
the order, as baboons and some species of macacus , 25 the 
upper portion of the ear is slightly pointed, and the 
margin is not at all folded inwards ; but if the margin 
were to be thus folded, a slight point would necessarily 
project inwards and probably a little outwards. This 
could actually be observed in a specimen of the Ateles 
beelzebuth in the Zoological Gardens ; and we may safely 
conclude that it is a similar structure— a vestige of 
formerly pointed ears — wdtich occasionally reappears in 
man. 
The nictitating membrane, or third eyelid, with its 
accessory muscles and other structures, is especially 
well developed in birds, and is of much functional im- 
portance to them, as it can be rapidly drawn across the 
whole eye-ball. It is found in some reptiles and amphi- 
bians, and in certain fishes, as in sharks. It is fairly 
well developed in the two lower divisions of the mam- 
malian series, namely, in the monotremata and marsu- 
pials, and in some few of the higher mammals, as in the 
walrus. But in man, the quadrumana, and most other 
mammals, it exists, as is admitted by all anatomists, as 
a mere rudiment, called the semilunar fold . 26 
The sense of smell is of the highest importance to 
the greater number of mammals— to some, as the rumi- 
nants, in warning them of danger ; to others, as the 
23 See also some remarks, and the drawings of the ears of the Lemu- 
roidea, in Messrs. Murie and Mivart’s excellent paper in L Transact. 
Zoolog. Soc.’ yoI. vii. 1869, pp. 6 and 90. 
26 Muller’s ‘Elements of Physiology,’ Eng. translat., 1842, vol. ii. p. 
1117. Owen, 1 Anatomy of Vertebrates,’ vol. iii. p. 260 ; ibid, on the 
Walrus, ‘ Proc. Zoolog. Soc.’ November 8th, 1854. See also R. Knox ? 
4 Great Artists and Anatomists,’ p. 106. This rudiment apparently is 
.somewhat larger in Negroes and Australians than in Europeans, see Carl 
Vogt, ‘ Lectures on Man,’ Eng. translat. p. 129. 
