18 THE POUCHED MOLE 



in which this mole works forms an environment incom- 

 patible with any functional eye, which would be speedily 

 destroyed by irritation and inflammation. Nature has 

 made an effort to preserve the organs by abnormal 

 development of the lachrymal duct communicating with 

 the nasal cavity, whereby the chamber might be cleansed 

 more effectively of sand, but the effort has failed. The 

 failure seems likely to be fatal to the preservation of the 

 species; the pouched mole already is practically blind, 

 though still sensible of the difference between dark and 

 daylight. Yet eyesight, one must suppose, is more 

 essential to the welfare of the ruddy-coated Australian 

 mole than to our own sooty -garbed ' mowdie/ because, 

 whereas the true mole burrows deep, and is very seldom 

 seen alive aboveground, the Notoryctes of the southern 

 hemisphere works so near the surface that Mr. Lydekker 

 has aptly compared its rapid movement through the sand 

 to that of a porpoise through a smooth sea. The back of 

 the animal may be seen appearing at frequent intervals 

 in its course. It is not surprising, therefore, to learn that 

 the pouched mole is already exceedingly rare, and appears 

 to be on the verge of extinction in consequence of its 

 peculiar infirmity. 



Now, in what manner does this failure of nature to 

 preserve the eyesight of the pouched mole, and the 

 approaching disappearance of the genus, bear upon the 

 general disappearance of the marsupial type of mammal 

 from all the world except Australia? This mole has 

 become disabled in the struggle for existence by means of 

 an external physical agency which has extinguished its 

 eyes. It is not extravagant to assume that a similar 

 agency prevailed to put an end to pouches. It is con- 



