BOOK XI. Lii. 140-LIV. 143 



among birds the variety of the heron class called in 

 Greek white herons " are said to lack one eye, and 

 to be a very good omen v.hen they fly North or 

 South, as they tell that dangers and alarms are being 

 dissipated. Nigidius says that also locusts and 

 cicadas have no eyes. For snails their pair of horns 

 fill the place of eyes by feehng in front of them. 

 Earth-worms also and worms in general have no 

 eyes. 



LIII. Man alone has eyes of various colours, 

 whereas with all other creatures the eyes of each 

 member of a species are aUke. Some horses too have 

 grey eyes ; but in man the eyes are of extremely 

 numerous variety and difference — larger than the 

 average, medium, small ; prominent, which are 

 thought to be dimmer, or deep-set, which are thought 

 to see most clearly, as are those with the colour of 

 goats' eyes. 



LIV. Moreover some people have long sight but sight. 

 others can only see things brought close to them. 

 The sight of many depends on the brilHance of the 

 sun, and they cannot see clearly on a cloudy day or 

 after sunset ; others have dimmer sight in the day 

 time but are exceptionally keen-sighted at night. 

 We have already said enough * about double pupils, vaneties of 

 orpersons who have the evil eye. Bhie-grey eyes see "^^*^*' 

 more clearly in the dark. It is stated that Tiberius 

 Caesar alone of all mankind was so constituted that 

 if he woke up in the night for a short time he could 

 see everything just as in bright dayhght, although 

 darkness gradually closed over him. The late 

 lamented Augustus had grey eyes hke those of 

 horses, the whites being larger than usual in a 

 human being, on account of which he used to be 



