THE BIONOMICS OF ENGLISH OLIGOCHiETA 15 



development. The material must be moist, for as soon as it 

 begins to dry the worms disappear. The species found in 

 such localities include not only Claparede's P. semifuscus, 

 crassus, verrucosus, lacteus, and ebudensis, but L. litoreus, 

 lineatus, and evansi, together with M. georgiana, arenaria, and 

 a variety of others. They feed on the algae, sponges, zoophytes 

 and similar decaying material cast up by the tides, and in this 

 way act as an army of scavengers to clear away useless and 

 putrid matter. There is no part of the British coast where they 

 may not be found, if only the moist debris can be stranded 

 by the waves and kept in a sufficiently humid condition. 

 Much good service might be rendered to science by visitors to 

 the less frequented shores if they would forward to me in tin 

 boxes samples of the material to be collected in these localities. 1 



Drain Purifiers and Stream Workers. — A second group of 

 Pachydrilids is to be found associated with gutters, drains, and 

 ditches ; the muddy margins of ponds, streams, and rivers 

 where cattle drink, or into which the filth from large industrial 

 works, and the offal and sewage of towns and cities finds its 

 way ; and especially at our sewage works up and down the 

 land. It would be impossible to estimate the number of red- 

 blooded worms supported by the ooze of such a stream, for 

 example, as the Aire, which flows in the neighbourhood of 

 Bradford and Leeds. Should a collector go down to the margin 

 of the river at Apperley Bridge, for instance, and dip up a 

 handful of the greasy ooze, he would in all probability find it 

 teeming with life. There may be Tubificids or other worms 

 present, and in some instances white-blooded Enchytraeids 

 may be dominant, but as a general rule the bulk of the 

 scavengers will be species of Pachydrilus. By way of contrast 

 it may be noted that at Burton-on-Trent, where there is a 

 clean margin to the river, no such worms are to be found. 



What is true of the Aire and similar rivers applies also to 

 the streamlet into which the drainage of a country village flows. 

 Let the mud, refuse, roots of grass, or floating debris be examined 

 and the wealth of annelid life will be amazing. As concrete 

 illustrations are better than mere postulates, let me give an 

 example. About three miles from Ashby-de-la-Zouch is the 

 secluded village of Blackfordby through which flows a tiny 

 rill. It is this watercourse which supplies much of the drinking 

 1 Address : Department of Zoology, Birmingham. 



