332 



MANUAL OF ZOOLOGY. 



impossible to place Peripatus amongst the Annelida, and the 

 affinities of the genus appear to be closer with the Myria- 

 pods than with any other group ; though the wide separation 



Fig. 173. A, Peripatus Edwardsit, magnified two diameters. B, Head, viewed from 

 below, enlarged five times. C and D, A single foot, viewed from above and sideways, 

 enlarged. (After Grube.) 



of the ventral nerve-cords, along with other points, removes 

 Peripatus to a considerable distance from the normal forms 

 of the Myriapoda. If Peripatiis should ultimately be retained 

 in the Myriapoda, it would be as well, for the sake of 

 uniformity, to change Grube's name of Onychophora to that of 

 Onychopoda. 



DISTRIBUTION OF MYRIAPODA IN TIME. About twenty 

 species of Myriapoda are known as fossils, the oldest examples 

 of the order having been found in the Carboniferous epoch. 

 From rocks of this age several species of Chilognathous Myria- 

 pods have been discovered. The best-known forms belong to 

 the genera Xylobius and Archiulus, and have been placed in a 

 special family under the name of ArchiulidcE. The occurrence 

 of air-breathing articulate animals (both Arachnida and Myria- 

 poda) in the Carboniferous period is noticeable, as being con- 

 temporaneous with the earliest-known terrestrial Molluscs. 



