264 



ZOOLOGY 



of being in pairs, one on each side 

 of each segment. Since the form of 

 the tracheae and other structural 

 features in the Peripatus are very 

 unlike those of the typical tra- 

 cheate arthropods, such as the 

 insects, it is evident that we can 

 regard the Prototracheata only as 

 a relatively primitive type, not in 

 any sense as truly ancestral. It 

 is a branch from an early stock 

 which came off very long ago, and 

 has been modified in its own way, 

 which is not the way of the insects 

 Distribution or spiders. At the present time 

 the species are widely scattered 

 and generally rare, as is usually 

 the case with an ancient and 

 waning stock. When alive, the 

 Peripatus is a very handsome 

 animal, with a soft, velvety skin, 

 which in some species is very 

 beautifully colored with subdued 

 shades of reddish or greenish. 

 The numerous pairs of soft legs 

 remind one of the abdominal legs 

 of a caterpillar, while the soft, 

 flexible antennae are not unlike the 

 tentacles of a snail or slug. The 

 form figured was found in South 

 Africa. No kind of Peripatus is 



FIG. 77. Peripatus (Peripatopsis) capensis, X 3 ; 

 viewed from the dorsal surface. The largest speci- 

 men recorded was 65 mm. long. 



After drawing by Miss Balfour 



