194 OLIGOCHAETA 



Moniligastef ; a fuller description of its structure will be found on a preceding 

 page (p. 119). The ovaries usually occupy an abnormal position — abnormal, that is 

 to say, as compared with 'earthworms,' where they are invariably in the thirteenth 

 segment ; this statement, however, only applies to certain species of Moniligaster, where 

 the ovaries occupy segment xi ; in Besmogaster and in M. houteni and M. viridis 

 their position is different ; they lie in xiii ; there is of course a con-esponding 

 difference in the apertures of the oviducts. 



The Moniligastridae have very large egg-sacs — another point of resemblance 

 to many ' Limicolae ; ' as a general rule the fact that these structures, which 

 extend through several segments, are egg-sacs depends upon pi'obability ; their 

 position is such as to lead to the inference that that is their nature ; in M. 

 bahamensis, however, the egg-sacs were found by me (57) to contain numerous 

 ova ; these ova were not particularly large, a little larger than is common among 

 earthworms but nothing like the bulk of the enormous ova of the Tubificidae or 

 Lumbriculidae. Nevertheless they were crammed with large yolk particles, so much 

 so as to frequently obliterate the nucleus ; this fact may be an important point 

 of similarity to aquatic Oligochaeta ; but it must be admitted that it may only 

 point to the conclusion that the egg-sacs are not meant to store the ova but are 

 merely the receptacles of useless ova, which there undergo degeneration. There are 

 other facts which render this latter conclusion possible (see p. 96). In any case the 

 large size of the receptacula ovorum is, as I have pointed out, and as EosA (11) 

 has admitted, a resemblance to the freshwater Annelids. 



The fantily Moniligastridae is characteristically an old-world group ; it has been 

 met with in India, Ceylon, Sumatra, Borneo, Buynah ; quite recently, however, I have 

 described a species from the Bahamas. 



The affinities of the family are not so plain ; I have dwelt upon the resemblances 

 to the aquatic Oligochaeta — a resemblance which Rosa has sought to minimize. In 

 the following points the genus Moniligaster differs from earthworms and agrees with 

 the lower Oligochaeta: — 



(i) The sperm-ducts only traverse one septum on their way to the exterior, 

 and are much coiled, as in Pachydrilus for example. The doubling 

 of the sperm-duets in Besmogaster is not important, for this often 

 occurs. 

 (2) The spermiducal gland and the penis are constructed upon the plan 

 common to many ' Limicolae,' and different from that found in any 

 'earthworm.' This does not altogether apply to Besmogaster (but see 

 p. 119). 



