535 



being placed between two segments and upon the fact that the ovi- 

 ducts open behind the spermducts ; I admit the justice of this criti- 

 cism; he furthermore points out the discrepancies between my account 

 of the reproductive organs of M. Bartvelli and Horst's account" of 

 the same organs in 31. Houteni, which could be reconciled if it w^ere 

 proved that I had omitted to count two segments. I have since reexam- 

 ined my specimens both in longitudinal sections and a preparation of 

 the anterior end of the worm flattened out and mounted in Canada bal- 

 sam; the latter preparation shows me that I have made an error of one 

 segment. After the peristomial segment there is an extremely narrow 

 setigerous segment with setae so minute that they require a microscope 

 for their demonstration. The apertures of the atria are thus between 

 segment X/XI ; there is therefore some reason to regard the original 

 description by Ferri er of M. Deshayesi as being right in this parti- 

 cular. 



From this it appears that the difference in position between the 

 apertures of the spermducts of Moniligaster and the earthworm Tetra- 

 gonurus^ is reduced to one segment; this is perhaps hardly a sufficient 

 reason for refusing to accept K o s a 's placing of Moniligaster. But the 

 correction of this error does not invalidate the position that I have taken 

 up as to the affinities of the genus Moiiilig aster. 



I am unable to state what is the position of the testes but I should 

 imagine that they will be found to occupy the IX*** segment — possibly 

 attached to the posterior dissepiment of this segment. It is also difficult 

 to make out the relations of the single pair of spermsacs to dissepiment 

 IX — X and consequently the position of the vas deferens funnel is 

 obscure; it seems most probable that the spermsacs are really — as 

 they appear to be — contained partly in segment X and partly in seg- 

 ment IX : and that they correspond to the anterior and posterior out- 

 growth of the septum IX — X in the young Lumhricus (see Horn's 

 »Atlas of Practical Elementary Biology«, pi. XII fig. IX). In this case 

 the funnel of the vas deferens will be really in the IX*^^ segment. The 

 only alternative to this is that the vas deferens opens into the X'^ seg- 

 ment, i. e. the same segment as that which bears its external orifice. This 

 condition , as I have already pointed out is paralleled in Stylaria , but 

 the first alternative commends itself to me as the most probable. In 

 either case there is a great diff'erence from the conditions met with in 

 other earthworms. Furthermore the atrium as than already insisted 

 Tessembles the atrium of the Lumbriculidae and diff"ers from the corre- 



■^ Notes from the Leyden Mus. Vol. IX. 



8 It must be remembered however that we have no anatomical date with regard 

 to this senus. 



