MEGADRILI 



389 



Lutnbricus, Allolobophora, and Allurus. The American Bimastos 

 may be distinct. Tetragonurus, not allowed by some, is at present 

 unknown except as regards external characters ; it differs from 

 the other Lumbricidae in the fact that the male pores are upon 

 the twelfth segment. In Allurus they are upon segment 13, and 

 in the remaining genera upon the fifteenth. Lumbricus is to be 

 distinguished from Allolobophora by its prostomium, which is 



FIG. 199. AlloloboplwrachlorolicaSfivigny. 

 x 4. The clitellar segments are marked 

 in Roman numerals, t.p, Tubercula 

 pubertatis ; 6, male pore. 



FIG. 200. Alloktiophvra putris Vejd. 

 x 5. Lettering as iu Fig. 199. 

 The black dots represent the chaetae 

 in both figures. 



continued by grooves on to the buccal segment, so as to cut the 

 latter in half. It has also median sperm reservoirs, as well as 

 the paired sperm sacs which are alone present in Allolobophora. 



This is the only family of earthworms which, so far as is 

 known, can brave the ice arid snow, and what is still more 



