STRUCTURE OF A GENUS OF OLIGOCH^ETA. 9 



this portion of the oviduct was as yet developed in the specimen, which I have already 

 shown some reasons for regarding as very immature. The relations of the oviducal funnel 

 are illustrated in fig. 8. It is important to notice that the position of the funnel does 

 not agree with that of the vas deferens funnel. 



III. Affinities and Systematic Position of Moniligastek. 



The first question which arises is, Are all the species which have been described under 

 this name congeneric ? This question is raised in consequence of the suggestion of Dr 

 Rosa [14], that M. Deshayesi of Perrier " is not only specifically but generically distinct 

 from the other species." Dr Rosa does not state in this paper his reasons for this view, 

 with which I am myself inclined to disagree ; of course, if Dr Horst and I are wrong in 

 regarding the anterior pair of testes and vasa deferentia of Perrier's species as sperma- 

 thecse, Moniligaster Deshayesi is not congeneric with M. Houteni and M. Barwelli, but 

 this does not appear to me any more than to Dr Rosa to be likely ; accordingly, I consider 

 that this group of worms consists of only one genus — Moniligaster. 



The next point is, Does the genus Moniligaster agree more closely with the "Terricolse " 

 as defined by Rosa than with any other group of Oligochseta, and is this agreement 

 sufficiently close to warrant its inclusion in the family Terricolse ? or should it rather 

 be regarded as a family equivalent to Terricolse ? 



The Terricolse are defined by Rosa [14] as follows : — * 



1. Two pairs of testes in 10 and 11 (first sometimes wanting). 



2. One to four pairs of sperm sacs formed by outgrowths of dissepiments 9/10, 10/11, 



11/12. 



3. Vasa deferentia generally two on each side, only one if the testes are single, open- 



ing by funnels into segments containing testes. 



4. A pair of ovaries in 13. 



5. A pair of oviducts opening internally into 1 3. 



6. Generally [? always] a pair of receptacula ovorum produced by an outgrowth of 



dissepiment 13/14. 



7. A various number of spermathecse (except in Criodrilus)A 



With some apparent exceptions in various points, such as Microchosta (in position of 

 vas deferens funnels), which Rosa is inclined to doubt will prove to be real exceptions 

 when submitted to reinvestigation, all earthworms are stated to conform to this definition. 



I would remark, in the first place, that the above definition hardly excludes Phreoryctes. 

 Add another pair of ovaries and oviducts opening into 12th segment (which sometimes 

 are present in earthworms), and Phreoryctes, becomes at once one of Rosa's " Terricolse." 

 But surely the organisation of the reproductive system in Phreoryctes does not point to 



* I only give a condensed epitome, to save apace. 



t And some few other species, as Rosa and I have lately shown. 



VOL. XXXVI. PART I. (NO. 1). B 



