386 OLIGOCHAETA 



genus are often very great. We have already referred to the 

 remarkable branching of the nephridial duct in the body-wall, 

 and to the much modified calciferous glands of Stuhlmannia and 

 some other genera. These structural variations perhaps permit 

 the family to be divided into two sub-families. In one there are 

 calciferous glands of the normal type, though peculiar in that 

 one or more are median and ventral in position, and are unpaired ; 

 there is no branching of the nephridium in the body- wall ; there 

 are always, so far as is known, the Pacinian-corpuscle-like bodies in 

 the integument. In the other sub-family the calciferous glands, 

 if present (they are absent, for instance, in Libyodrilus), have under- 

 gone much modification in structure ; the nephridia, where they 

 have been investigated, have been found to branch copiously in 

 the body-wall ; the peculiar integumental bodies hardly ever occur. 

 FAM. 13. Geoscolicidae. 1 This family is essentially tropical, 

 being found in South America and the West Indies, in tropical 

 Africa, in India, and in some of the islands of the Malay Archi- 

 pelago. But it also occurs (Sparganophilus and Criodrilus) in 

 Europe and in America. A good many of the genera are aquatic. 

 This is the case with the two already mentioned ; the genera 

 Glyphidrilus and Annadrilus of the Malay Archipelago can live in 

 water. The family is easily definable if we take the more typical 

 forms ; but at one end of the series it fades into the next family, 

 that of the Lumbricidae. Criodrilus is one of the genera which is 

 difficult to place. As is the case with many Geoscolicidae, Crio- 

 drilus has ornamented chaetae not only upon the clitellum, but 

 upon the other segments of the body. This character was until 

 recently unknown among the Lumbricidae; it has been lately 

 found in Allololophora moebii and A. lonnbergi. The absence 

 of sperrnathecae characterises Criodrilus as well as other Geoscoli- 

 cidae ; but here again the character is not by any means distinc- 

 tive, for in Allolobopkora constricta there is the same absence of 

 these organs. In Criodrilus the male pores are upon segment 15, 

 as in the Lumbricidae, but a species of Kynotus, which is certainly 

 a Geoscolecid, has these pores upon precisely the same segment. 

 The only point in which Criodrilus is definitely a Geoscolecid, or 

 rather not a Lumbricid, is in the forward position of the clitellum, 

 which begins upon the fifteenth segment, far earlier than it does 



1 The scattered literature of this family is due to Benham, Michaelsen, Perrier, 

 Rosa, and others. 



