DESCRIPTIONS OF GENERA AND SPECIES 195 



(3) The forward position of the male-pores. 



(4) The minute structure of the clitellum and its forward position. 



(5) The large size of the egg-sacs, and the great abundance of yolk in 



the ova. 



Even if we follow ROSA in placing but little stress upon the shifting forward of 

 the clitellum and the male-pores, there remain a number of facts in the anatomy 

 of the Moniligastridae which indicate differences from all other earthworms, and 

 similarities to the lower Oligochaeta. 



BENHAM (1) places the family upon the direct line of evolution of the higher 

 from the lower Oligochaeta, thus admitting their affinities to the latter. I have 

 already discussed the way in which this evolution has most probably taken place, 

 viz. in the reverse direction from that believed in by BENHAM ; but there still 

 remains the question to which group of the higher Oligochaeta are the Monili- 

 gastridae most nearly related. Ros\ (20) suggests the Geoscolicidae and Lutnbricidae ; 

 but is not able to bring forward many facts in support of this contention. The 

 principal matter upon which he dwells, in comparing the family to the Geoscolicidae, 

 is the intersegmental position of the male-pores ; the presence also of caeca to the 

 nephridia is referred to, though this is also met with among the Acanthodrilidae ; 

 but it is thought by ROSA that there are also affinities in this latter direction. 

 As regards the Lumbricidae he compares the Moniligastridae chiefly with Allurus and 

 Tetragonurus ; this comparison is made on account of the forward position of the 

 male-pores ; the posterior gizzards are also mentioned as a point of similarity to the 

 Lumbricidae ; but we now know that more than one genus belonging to quite different 

 families have the same character, viz. Pleionogaster, and Hyperiodnlus, &c., among 

 the Eudrilidae. The forward position of the male-pores may well be, as ROSA thinks, 

 a reason for associating the family Moniligastridae with the Lumbricidae ; but it is 

 surely not quite fair to deny this point of likeness to the Lumbriculidae, &c., and to 

 claim it for the Lumbricidae! On an earlier page of his paper dealing with 

 Desmogaster (11\ in which these matters are subjected to a renewed discussion, ROSA 

 quotes the example of Buchholtzia appendiculata to discount the strength of the 

 arguments derived from the forward position of the clitellum in Moniligaster. 



Other points of resemblance to the Geoscolicidae hardly exist 1 , and it does not 

 seem that the mere position of the male-pores is a likeness of Krst-rate importance ; 

 the only conclusion to which we can, in the present state of our knowledge, come 

 is that the Moniligastridae form an isolated group, with general affinities to the 



1 Ornamented setae have been found in so many groups; but it must be admitted that they aia 

 characteristic of the Ueoscolicidae. In the present family they occur in M. 



C 2 



