EYE OF NOTORYCTES TYPHLOPS. 569 



came finer and the temperature higher^ its eye would still 

 further degenerate very rapidly with the increased liability 

 to irritation. This also confirms the previously expressed 

 opinion with regard to the cause of the degeneration of the 

 eye of the Notoryctes. 



In the eye of Notoryctes, then, we have an example of a 

 very specialised sense-organ, degenerating in virtue of its en- 

 vironment, losing its original sensory function, and assuming 

 an importance of quite a mechanical nature, also rendered 

 necessary by reason of the habitat, and, further, this trans- 

 ference of function is even now in an incomplete and transi- 

 tional stage, though it has in some animals reached a point 

 of reduction not known in any other Vertebrate eye. 



I understand that the brain of the Notoryctes is being in- 

 vestigated, and it will be of great interest to note whether 

 the sensory nuclei in the optic centres have kept pace with 

 the degeneration of their peripheral end-organ. 



Biological Laboiiatoky, 



Melbourne University; 



February Uth, 1906. 



Bibliography. 



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