50 
pltny's katueal histoky. 
[Book XI. 
of the blessings of sight, distinguish life from death. Eyes, 
however, have not been granted to all animals ; oysters have 
none, but, with reference to some of the shell-fish, the question 
is still doubtful ; for if we move the fingers before a scallop 
half open, it will immediately close its shell, apparently from 
seeing them, while the solen^^ will start away from an iron 
instrument when placed near it. Among quadrupeds the 
mole^^ has no sight, though it has something that bears a re- 
semblance to eyes, if we remove the membrane that is ex- 
tended in front of them. Among birds also, it is said that 
a species of heron, which is known as the *^leucus,"^° is 
wanting of one eye : a bird of most excellent augury, when 
it flies towards the south or north, for it is said that it 
portends thereby that there is about to be an end of perils and 
alarms. Mgidius sa^^s also, that neither locusts nor grass- 
hoppers have eyes. In snails, the two small horns with which 
they feel their way, perform the duties of eyes. Neither the 
mawworm^^ nor any other kind of worm has eyes. 
CHAP. 53. THE DIVEESITY OF THE COLOUR OF THE EYES. 
The eyes vary in colour in the human race only ; in all 
other animals they are of one uniform colour peculiar to the 
kind, though there are some horses that have eyes of an azure 
colour. But in man the varieties and diversities are most 
numerous ; the eyes being either large, of middling size, re- 
markably small, or remarkably prominent. These last are 
generally supposed to be very weak, while those which are 
deep-seated are considered the best, as is the case also with 
those which in colour resemble the eyes of the goat. 
CHAP. 54. THE THEOEY OF SIGHT — -PEESOl^S WHO CAIs^ SEE EY 
NIGHT. 
In addition to this, there are some persons who can see to a 
^« Or razor-sbeath. See B. x. c. 88. 
89 Aristotle was of this opinion, but Galen maintained that tbe mole can 
see. Its eye is extremely small, and bard on tbe surface. 
90 Or white heron. As Cuvier remarks, this is probably a mere 
augur's fable. 
^ It is almost needless to remark, that both snails, as well as locusts and 
grasshoppers, have eyes. 
^ Lumbricus. 
