CAPE OF GOOD HOPE. 159 



in Tertiary times, and their beaks being so dense in structure as to 

 be readily preserved as fossils, are common in such deposits as the 

 Eed Crag of Suffolk. I had the good luck to procure another 

 Ziphioid at the Falkland Islands during the voyage, near Port 

 D arwin. 



I stayed at the hotel at Wynberg for a fortnight, whilst 

 working at the anatomy and development of Peripatus capensis. 

 Peripatus is an animal of the very highest importance and 

 antiquity, and I believe it to be a nearly related representative 

 of the ancestor of all air-breathing Arthropoda, i.e., of all insects, 

 spiders, and Myriapods. 



The animal has the appearance of a black caterpillar, the 

 largest specimens being more than three inches in length, but 

 the majority smaller. A pair of simple horn-like antennae 

 project from the head, which is provided with a single pair 

 of small simple eyes. Beneath the head is the mouth provided 

 with tumid lips and within with a double pair of horny jaws. 

 The animal has seventeen pairs of short conical feet, provided 





peripatus capensis. (Natural size.) 



each with a pair of hooked claws. The skin of the animal 

 is soft and flexible, and not provided with any chitinous rings. 



The animal breathes air by means of tracheal tubes like 

 those of insects. These, instead of opening to the exterior by a 

 small number of apertures {stigmata) arranged at the sides 

 of the body in a regular manner as in all other animals provided 

 with tracheae, are much less highly specialized. The openings 

 of the short tracheae are scattered irregularly over the whole 

 surface of the animal's skin. 



It appears probable that we have existing in Peripatus 

 almost the earliest stage in the evolution of tracheae, and that 

 these air tubes were developed in the first tracheate animal out 

 of skin glands scattered all over the body. In higher tracheate 

 animals the tracheal openings have become restricted to certain 

 definite positions by the action of natural selection. 



