MONOGRAPH OF THE GENUS PERIPATTJS. 435 



The chief result of my observations has been to establish a 

 definite series of characters which distinguish quite sharply all 

 the species found in one region of distribution from those found 

 in the others. Excluding the doubtful case of the Sumatran 

 species, Peripatus has been found in the Ethiopian region 

 (South Africa), the Australasian, and the Neotropical regions, 

 and in each of these regions the genus is represented by more 

 than one species. I have been able to establish a certain 

 number of new species, but on the whole I must confess to 

 failure in this respect. My failure chiefly relates to the species 

 from the Neotropical region, and is due to the insufficient 

 number of specimens at my disposal. It is remarkable of the 

 species from this region that the number of the walking legs 

 varies considerably within the same species, and it is only 

 possible to determine the limits of the variation by examining 

 a large number of individuals. Inasmuch as the specific 

 characters other than those afforded by the legs are extremely 

 inconspicuous, the importance of having a large and well 

 preserved material is obvious — large in numbers to enable one 

 to establish the limits of leg variation, and well preserved that 

 the more minute specific differences may be made out. 



How inconspicuous the specific characters are is well shown 

 by contrasting the South African species Capensis and 

 Balfouri. That these are distinct species is proved by the 

 fact that the number of legs is constant in all the large number 

 of specimens examined, and by the fact that it is preserved in 

 the reproduction of the species. Embryos removed from 

 P. capensis have invariably seventeen pairs of legs, while 

 embryos removed from P. Balfouri have invariably eighteen 

 pairs. The other differences relate simply to the texture and 

 tint of the skin, and are so minute as to escape any but the 

 experienced eye. 



Before concluding this introduction, I am desirous of pointing 

 out how extremely loose and inaccurate have been the observa- 

 tions of some professed zoologists on the members of our 

 genus. In several cases has it happened that the observer 

 (sit venia verbo) has not been at the trouble of counting the 



