SOME RECENT MEMOIRS UPON 

 OLIGOCH^TA. 



THE literature relating to this group of worms is 

 summed up in my Monograph of the Oligochceta 

 lately issued by the Clarendon Press ; but so energetic are 

 the unfortunately somewhat few workers in this particular 

 subject that new facts have gone on accumulating with some 

 rapidity since the publication of that work. It is my 

 intention in the present article to offer the reader a re'sume 

 of this latest work with, naturally, some references to what 

 has gone before. 



It is agreed by all those who are acquainted with the 

 terrestrial Oligochaeta that their peculiar mode of life, their 

 susceptibility to sea water, and the comparatively few 

 chances of dispersal enjoyed by them, render their distribu- 

 tion highly important in estimating the relations between 

 land masses now and in the past. This has an especial 

 bearing upon the theory of the former northward extension 

 of the Antarctic Continent, a matter upon which much has 

 been written lately. To deal adequately with this large 

 question would of course demand more space than can be 

 allowed me. I shall content myself with referring solely to 

 the evidence which is forthcoming from the study of earth- 

 worms. Fortunately we are in possession of a considerable 

 amount of information about the terrestrial Olioochaeta of 

 New Zealand and Patagonia ; the former country indeed 

 must be regarded as being better known perhaps than any 

 quarter of the globe, excepting of course Europe. The 

 extensive collections lately made by Dr. Michaelsen in 

 South America have added largely to the number of species 

 brought back by his predecessors. It results from an 

 examination of the species found in the two countries that 

 in both of them the prevailing types belong to the genera 

 Acanthodrilus and Microscolex, particularly the former. Of 

 the thirty-two indigenous species at present known from 

 Patagonia and the more southern parts of the South Ameri- 



