176 EFFECTS OF MIRAGE. 



Down the centre of the back, ran a streak of black, 

 which was also the colour of the extremity of 

 its slightly bushy tail. The face and belly were like- 

 wise darker than other parts of the body, and the 

 feet were black and well cushioned, giving it a firm 

 hold of the rocks over which it bounded with sur- 

 prising agility, through it never ran very far, 

 always popping into the cavities caused by the loose 

 manner in which the blocks forming the island are 

 thrown together.* 



The specimen of the species of Helix I have 

 above mentioned was found by Mr. Dring, one of 

 our most successful collectors in that department. 

 In the Appendix are figured some of the new shells 

 discovered during the voyage. 



Leaving Depuch Island, we examined the coast to 

 the eastward as far as the Turtle Isles, a distance of 

 eighty-five miles, the first twenty-seven of which 

 trended N. 55° E,and the remainder N. 67° E. curv- 

 ing slightly inwards. As the French had obtained a 

 distant view of this coast, it did not possess to us the 

 interest of being a new portion of the continent. Still 

 the effect of the treacherous mirage, which has often 

 deluded the way-worn thirsty traveller with the false 

 appearance of water, raised many parts of the interior 



* Mr. Gould has figured an animal very like this I have 

 described, as Petrogale Lateralis, or the Stripe-Sided Rock 

 Wallaby, from a specimen he some time afterwards got from 

 Western Australia ; but he has not noticed the beautiful 

 kangaroo of Depuch Island. 



