THE BIONOMICS OF ENGLISH OLIGOCH^TA 101 



or at most a dozen species. To-day the figure stands at forty 

 and upwards, and there are doubtless still several discoveries 

 to be made in our gardens, islands, and mountains. It is with 

 these forty species that we are immediately concerned. 



Rarity and Frequency. — It must not be assumed that they 

 are all generally distributed over the British Isles. In a few 

 instances the species is represented by a solitary specimen, 

 and in others, while the number of specimens is unlimited, 

 they are at present known in only one locality. While many 

 are common throughout the country, as well as in Europe, 

 others have a range which is very instructive. Let us take 

 a few examples. In 1892 I wrote to Dr. Rosa of Turin to the 

 effect that a new worm (Lumbricus papillosus Friend) had turned 

 up in Ireland. He alludes to it in an appendix to the genus 

 Lumbricus (op. cit. 27), and notes incidentally that the name 

 had already been appropriated by O. F. Muller. On this 

 account Cognetti afterwards changed it to Lumbricus friendi. 

 This species has been sought unceasingly in every part of 

 England, Scotland, and Wales without a trace being found, 

 yet I no sooner landed in Dublin in March last and began my 

 researches than it turned up in plenty. In 1890 Michaelsen 

 placed it in his list of species, and recorded it for Switzerland, 

 while Southern has more recently remarked that " L, friendi 

 is common in the south of Ireland. On the Continent it is 

 markedly alpine in its range, and is only found at considerable 

 elevations in the Pyrenees and the Alps." In the light of 

 Taylor's recent paper on " Dominancy in Nature" this is most 

 instructive. 



We may compare with this the distribution of another of 

 our British Lumbricidae, which, so far as I am aware, has never 

 been studied by any other investigator but myself. In 1910 

 I was spending Easter at Bridlington, and found a solitary 

 specimen of Octolasium gracile Oerley. It was new to Britain, 

 and would seem to be gradually working towards the west. 

 Up till the present it has never been found in Ireland, Wales, 

 or the West of England, and in Scotland and the Midlands is 

 very rarely seen. Yet in the autumn of 191 1 it was the dominant 

 Lumbricid at Sutton Broad in East Anglia, and in Epping 

 Forest and elsewhere in the south and east it is quite gre- 

 garious. Unfortunately Michaelsen confuses it with O. lacteum, 

 from which, in England at least, it is absolutely distinct ; and 



