360 W. L. SCLATEE. 



regards as homologous with the nephridial funnel of the genital 

 segment and its vesicle. This structure is entirely absent in 

 the Cape species of Peripatus. 



Also in the South American species the generative opening 

 lies between a pair of well-developed legs, while in the Cape 

 species the legs of the generative segment are rudimentary or 

 represented only by the anal papillae. 



In the New Zealand species the legs of the generative 

 segment are well developed, but the question of the presence 

 or absence of the receptaculum ovorum does not seem to be 

 quite settled. 



These are the only really important anatomical differences 

 between the three groups of Peripatus as far as is at present 

 known. 



The only other instance of such great variation in develop- 

 ment between such nearly allied forms which I can call to 

 memory is that of Bateson's Balanoglossus, which in its deve- 

 lopment differs largely from the ordinary Tornaria balano- 

 glossus. 



This, however, is easily explained by the difference of the 

 habits of the two forms ; Bateson's larva is a mud-living animal, 

 while Tornaria is pelagic. 



The curious thing about Peripatus is that, as far as is known, 

 its habits and mode of life are much the same all over the world, 

 so that the striking differences in the development of the three 

 forms cannot be explained by change of habits modified by 

 external conditions. 



In conclusion, I wish to apologise to my readers for the in- 

 completeness of my work, and for my uncertainty on many im- 

 portant points; my excuse is the want of time and the absence of 

 material, since a portion of that which I brought from Demerara 

 was not satisfactory. And as it seemed unlikely that for some 

 time at least anyone would be able to procure more material, 

 either alive or with the uterus adequately preserved, I have 

 thought it better to publish the small contribution that I have 

 been able to make towards our better knowledge of that most 

 ancient and interesting of all living Arthropods — Peripatus. 



