ONYCHOPHOllA OF WEST AUSTRALIA. 



387 



legs or the presence or absence of an accessory tooth on the outer 

 mandibie-blade. Surely some such change as this could hp.ve 

 occurred as a mutation over and over again. In any case the 

 West Australian species occurs in two forms, one with 16 and 

 one with 15 pairs of legs, so that the resemblance to P. suteri 

 does not hold good. 



As a matter of fact Peripatoides occidentcdis approaches most 

 closely Peripatoides leuckartii, and in addition to the resem- 

 blances noted by Bouvier we may add that receptacula seminales. 

 are present in both forms. The species is, however, very distinct 

 from all other Peripatus species, and thus from all the other 

 Australian species (which is not surprising seeing that the two 

 Peripatus regions are separated by over two thousand miles, the 

 greater part of which is country quite uninhabitable by Peripatus) 

 in the presence of extraordinarily long crural glands opening on 

 the first pair of legs. The northern variety is the only known 

 Peripatus in Australia having 16 pairs of legs. 



SUMMARY OF RESULTS OF GENERAL IMPORTANCE. 



{i. e. probably applicable to most if not all species of 

 Onychophora.) 



I. The cells of a certain part of the so-called nepliridium — 

 that which opens into the terminal coelomic vesicle — bear 

 long and well-developed cilia. Thus cilia occur in the 

 excretory ducts of Peripatus as well as in the repro- 

 ductive organs. 



11. Ci'ural glands do sometimes occur in the female, but do 

 not seem to possess any ducts. 



III. The tracheae of Peripatus possess a characteristic spiral 



supporting fibre. 



(This has been a disputed question for many years.) 



IV. The tracheae of Peripatus, although running a separate 



course for some distance from the tracheal pit, eventually 

 branch (see PI. II. figs. 7 & 8). 

 V. Spermatogenesis does not take place in the testis but in 

 the seminal vesicles. This discovery, made originally 

 by Gafl:Von, seems to have been lost sight of in most 

 descriptions of Peripatus. 



LITERATURE CITED IN TEXT. 



1. Balfour. — Anatomy and Development of Peripatus capensis. 



Q.J. M.S. 1883. 



2. Bouvier. — Monographic des Onychophores. Ann. des Sci. 



Nat. (9) 2 iS: 5. Paris, 1905 & 1907. 



3. Bouvier. — Onychophora. Die Fauna Siid-West Australiens, 



Bd. ii. Lief. 18. Jena, 1909. 

 Proc. Zool. Soc— 1920, No. XXYI. 26 



