A NEW EARTHWORM. 193 



Gardens, though it is common among exotics. All who have studied 

 certain Perichgets know that they have a habit of doubling themselves 

 like a fish about to leap, then with a sudden rebound flinging them- 

 selves to a considerable distance. This is the habit of D. merciensis, 

 and I have also observed it in certain species of white worms (Enchy- 

 trteids), but at present we know too little of the past and present life- 

 history of worms to be able to suggest the reason for this peculiarity. 

 In one specimen which I captured the tail consisted of only 

 twenty segments instead of sixty or eighty, but the length was only 

 a little short of the normal. The extension had been secured by 

 triannulation of the segments, so that each one was nearly three times 

 as broad as the type. This curious fact, which I have constantly 

 seen confirmed in other species, is very suggestive. We know too 

 little about the life processes among the lower animals to dogmatize 

 as to the meaning of this, but it would seem that a certain average 

 length of tail is necessary for each kind of worm to enable it properly 

 to work up the material which passes through its body. In most 

 British Earthworms there is a gizzard occupying two segments in 

 front of the girdle. Behind these segments (usually about the 17th 

 or 18th) the intestine runs right through the body to the posterior 

 extremity. It contains a curious invagination known as the " typhlo- 

 sole," and a certain amount of research has been carried out by one 

 or two physiologists with a view to ascertaining what changes the 

 food undergoes in passing along the intestine. I do not, however, 

 know that anything has been done to show why a certain length of 

 tail is necessary. This is only one of the many problems which the 

 study of earthworms suggests, and it has an important bearing on 

 agricultural and other questions. 



I am waiting for an opportunity to dissect the new worm, and 

 give details of its internal anatomy. This is necessary before one 

 can finally settle the genus, but there can be little doubt on that 

 point when all the external evidence has been weighed. Meanwhile 

 I may conclude with a brief summary : — 



D. MBECiENSis, Friend. — Length, two or three inches ; warm 

 brown or chestnut coloured dorsally, the ventral surface without pig- 

 ment. Head entirely cutting the first segment, as in Litmbrictis , 

 though not so deeply. Girdle from the 22nd to 31st segment (a total 

 of ten) ; without tubercula ; fused on the back when fully mature, 

 segments 22 and 23 being the last to be affected. Male pores on 

 segment 15 clearly seen, but not attended by swellings or papillee. 

 Dorsal pores large, beginning in intersegment |, but not seen on the 

 girdle (as they are, for example, in Eisenia rosea, Sav.) when fused. 

 Moves, when irritated, by powerful jerks. Habitat : Leaf-mould by 

 woods and in gardens, near Repton, the old capital of Mercia. 



Zool. 4th ser. vol. XV., May, 1921. 



