114 



Memoirs of the Indian Museum. 



[Vol. I, 



Systematic List of the Oli- 



gochaeta of India, Nepal, 



Ceylon, Burma and the 



Andaman Islands. 



Literature containing the best 

 description of the species. 



Localities of the 



species in this 



region. 



Further distribution 



of the genera and 



of the species. 



Biological cha- 

 racter of the 

 genera and 



faunistic 

 character of 

 the species. 



Peyichceta hulikalensis, 



BOURNE. 

 Perichœta lawsoni, BOURNE 



Perichœta viridis, SCHMAR- 

 DA. 



Perichœta [Pleurochœta ?) gra- 

 cilis, BOURNE 



A. G. BOURNE, in P. Z. S., 1886, p. 668 



A. G. BOURNE, ibid., p. 664 



L. SCHMARDA, in Neue wirbell. Th., i, 



2, p. 13, f. in the text, t. 18, f. 161. 

 A. G. BOURNE, in P. Z. S., 1886, p. 666. 



S. India, Nilgiri 



Hills. 

 S. India, Nilgiri 



Hills. 

 Ceylon, Belligamme. 



S. India, Nilgiri 

 Hills. 



.... 



.... 



DETAILED CONSIDERATION OF THE SPECIES IN VIEW OF THEIR 

 BIOI,OGICAIv AND FAUNISTIC CHARACTERS. 



In order to elucidate the more important faunistic features of the OHgochseta, we 

 must first arrange the whole of the genera and species according to their biological 

 characters. As I have stated in previous memoirs, the, migrations of nearly allied 

 genera may proceed in totally different directions and on totally different principles, if 

 their biological environment is different. In consequence of this the geographical 

 distribution of allied forms is not the same, if these forms, although united 

 in a single group by morphological characters, have a different biological habit. . For 

 instance, the geographical distribution of the littoral genus Pontodrihis is quite different 

 from, and not to be compared with, that of the very nearly allied but terrestrial genus 

 Plutellus -; while the regions to which limnic Oligochsetes are restricted are quite dif- 

 ferent from those of the most closely allied terrestrial forms ; for example, the limits 

 of the limnic Microchœtinœ (Tropical East Africa, India, Burma, Malay Peninsula, and 

 the Sunda Islands) differ from those of the terrestrial Microchœiinœ (South Africa and 

 Madagascar) . We will not get any clear idea of the features of geographical distribu- 

 tion, if we do not separate the species and genera according to biological habit very 

 sharply. The terrestrial Oligochsetes have to undergo a further sifting. Naturally they 

 are found living only in very restricted habitats, but many of them are liable to be ex- 

 ported by man and to settle in localities more or less distant from their original home. 

 These "peregrine forms" and their artificial distribution veil in a high degree 

 the characters of the autochthonic distribution which is generally much more simple. 

 On account of peregrine forms it was once possible to impute a circummundane dis- 

 tribution to the genus Pheretima, which is really restricted to the Indo-Malayan region. 

 Only on a basis cleared in this manner can we build with sufficient security further 

 conclusions as to the faunistic relations of the Oligochseta and the geological causes of 

 their present distribution. 



