A THREE-EYED REPTILE. 
257 
A THREE-EYED REPTILE. 
BY A. B. BADGER. 
Australia and New Zealand have long been celebrated for 
the remarkable character of tlieir fauna. They possess no 
representatives of the great families of mammals which 
inhabit other parts of the Old and New worlds, none of the 
Carnivora, of the Ungulata, of the Edentata, or of the 
Quadrumana; but in Australia, filling the places of these 
animals in the economy of Nature, we find numerous species 
of the Marsupials. In Australia, too, alone of all lands, 
lives that curious creature, half mammal, half reptile, the 
Ornithorhynclius, which lays an egg like a reptile, but has 
teats, and is covered with hair, like a mammal. New Zealand 
is much more deficient in animal life than Australia, but it 
possesses a reptile, Hatteria punctata , so peculiar that it has 
an order all to itself. In many respects it is very much like 
the lizards, in others it resembles the crocodiles; then, again, 
there are hooked processes on its ribs as there are on those of 
birds. The circumstance, however, with which we are now 
especiallyconcerned is the presence of three fully developed eyes. 
This wonderful fact was recently discovered by Mr. W. 
Baldwin Spencer, of Lincoln College, Oxford, and has been 
termed, by Professor Jeffrey Bell, the most remarkable 
discovery of the last twenty-five years. 
Two of these eyes are the ordinary lateral organs of 
Vertebrates, while the third is median, and lies on the 
surface of the brain at the bottom of a small hole perforating 
the parietal bone of the skull. It is, however, surrounded by 
connective tissue and is covered externally by the skin, so 
that the question arises of what use it can be to the animal. 
At present no answer can be given, but what is far more 
important, the existence of this eye in Hatteria has shown 
the homology* of a structure which is present in all Verte¬ 
brates, but the significance of which was hitherto unknown. 
The structure referred to is a small papilliform outgrowth from 
the upper surface of the brain, called the pineal gland, a name 
utterly misleading, as it has no secretory function; it is also 
better known as the epiphysis. In most Vertebrates it is simply 
composed of connective tissue, but in Hatteria Mr. Spencer f 
* Homology is the “ relation between parts in different animals 
which results from their development from corresponding embryonic 
parts.” (Darwin.) 
t Mr. Spencer’s attention was drawn to this subject through reading 
a paper by Graaf, a German observer, who had been working out the 
development of the epiphysis. 
