186 AKISTOTLE'S ANHOMCEOMEEIA 



This being so, it seems that the common mole, with its 

 small, jet-black eyes, in which no iris or sclerotic can be 

 seen, furnishes the best identification of the Aspalax. The 

 fact that its eyes can be seen through very small holes in 

 its skin, when the hairs surrounding them have been blown 

 aside, probably escaped Aristotle's notice. 



In connection with his statement about the eyes of 

 Aspalax being, as it were, injured during their development, 

 it may be stated that Mr. K. J. Lee says that the mole has, 

 at birth, eyes of a considerable degree of perfection, showing 

 an iris, white sclerotic, lens, and optic nerve, but that, as 

 the animal grows, it is deprived of the means of sight in 

 consequence of certain changes at the base of the skull.* 



From very early times, a belief in the total blindness of 

 the mole has been very persistent, ^sop, Aristotle, Cicero, 

 Virgil, Seneca, Pliny, Oppian of Syria, and several other 

 ancient authors refer to its blindness. Galen, however, 

 believed that the mole had a feeble sight. At a much later 

 time, Gesner, apparently following Albertus, says that there 

 is nothing wonderful in the mole being without eyes, for it 

 hunts worms in the earth, where eyes would be useless, and 

 yet it perceives, in some way, whether it is below or above 

 ground.! Aldrovandi says: — "I shall follow Scahger's 

 opinion, who attributes very weak sight to the moles, . . . 

 not in order to see under ground, but only to avoid the 

 light."! Finally, Owen asserted that, in the common mole 

 and especially in the blind mole, the eye is reduced to its 

 simple primitive office of taking cognizance of light, a filament 

 of the fifth nerve aiding a remnant of a proper optic nerve. § 



A belief in the total blindness of the mole is not un- 

 common in this country, and Mr. G. C. Zervos, writing 

 from Calymnos, informs me that modern Greeks consider 

 the mole to be blind. 



All classes of animals, Aristotle says, except his Ostraho- 

 derma and some other animals without blood, have eyes.H 

 He says, however, that solens try to escape downwards, when 

 they see anything pushed towards them, and that pectens 

 close their shells when anyone thrusts a finger near them, just 

 as if they could see.l' In many passages he mentions the eyes 



- Proc. Hoy. Soc. vol. 18, 1870, pp. 326, 327. 



f Hist. Anim. i. 1551, p. 105G. 



\ De Quadr. Digitat. Viviparis, dc, 1637, p. 452. 



§ Anat. Vertehr. vol. iii. 1868, p. 246. 



II H. A. i. c. 8, 8. 3. H Ibid. iv. c. 8, s. 18. 



