vi] PEREGRINE FORMS 99 



species, Moniligaster bahamenis, described some 

 years since from the Bahamas which must surely 

 be an example of a peregrine form, particularly since 

 it is probably identical with M. japonicus whose 

 name is indicative of its habitat. 



Among the huge family of the Megascolecidae 

 there are a considerable number of species which 

 apparently possess the same facilities for making 

 their way in different directions and across seas from 

 the locality that is thought to be their real home. 



Of the very many genera, however, of which this 

 family is composed, a comparatively small number 

 are thus peregrine in habit at times. All the species 

 known which are distributed broadcast, more or less, 

 over the tropics belong to the genera Pheretima, 

 Microseolex, Dichogaster, Megascolex, Perionyx, 

 Ocnerodrilus, Kerria. These several genera are 

 placed in order of frequency of exotic occurrence. 

 Indeed of the two latter genera their frequent life 

 in fresh water may really remove them from the 

 present category altogether. In addition to these 

 are some perhaps more questionable instances, such 

 as the genus Gordiodrilus which, prevalently West 

 African, has also been found in the West Indies, in 

 East Africa, and in India and Madagascar. These 

 instances I propose to leave out of consideration in 

 the present sketch. The most obviously peregrine 

 genus of all those enumerated is Pheretima, which 



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