vi] PEREGRINE FORMS 105 



there are cases such as Pheretima taprobanae which, 

 a native of Ceylon, is also found in Madagascar. 



It may be asserted in the third place that there 

 are no peculiarities of structure shared by all of 

 these peregrine forms which might account for their 

 physiological similarity, except indeed the somewhat 

 negative feature which they have in common, that is 

 of being of small or moderate size. Eudrilus and 

 Pontoscolex are not isolated types in their respective 

 families ; nor do they seem to approach each other in 

 any respect. Nor can it fairly be said that these 

 peregrine species are marked by any great variability 

 of structure as compared with other forms, which might 

 allow for their suiting themselves to various climates 

 and conditions. It is true that Eudrilus eugeniae has 

 received many names which might at first argue 

 some variability. But these names have been perhaps 

 given by persons rather under the influence of the 

 idea that remote habitat implied specific difference, 

 and who were thus inclined to see minute differences, 

 and who perhaps were furthermore led astray in the 

 matter by imperfectly accurate descriptions on the 

 part of others. Certainly some of the peregrine 

 species of Pheretima are subject to some variation, 

 particularly in the number and arrangement of their 

 genital pupillae. But this feature is by no means 

 confined to those species and cannot be utilised as 

 in any way an adaptation to wide distribution. 



