KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 15. N:0 7. 37 



In M. falciformis we find six pairs of ovanes all of about the same size, and of 

 the same degree of development, and all affixed to the body wall. Two pah's are 

 situated in the segments of the cingulum or the ll th and 12 th , one pair in front and one 

 pair behind the oritice of the efferent duct. All the other pairs are found behind the 

 cingulum or in the segments 13, 14, 15 and 16, one pair in each. 



In N. durus I found floating ovaries in the 9 th segment in front of the cingulum, 

 at the same time as the regular pair was affixed to the body wall of the segments 

 11 and 12. Floating ovaries have also been found by Claparede and others in E. ver- 

 micularis but situated behind the cingulum. That worm, considered so common, is 

 however perfectly unknown to me, and has hitherto not been found in Northern Europé, 

 or may even, like Lumbricus terrestris, be a collective species comprising several well 

 characterized forms. 



In species described by Clapakede, and also in some of those described here as 

 new, the eggs at the top of the ovary invariably develop tirst, and consequently all 

 the ripe or ripest eggs are seen in a row all round the edge of the ovary. 



But that is not always the case, as some species in that respect vary a good deal. 

 In M. primwvus the uppermost eggs are sometimes the most developed ones, but some- 

 times we find also the most advanced eggs in the centre of the ovary. 



In A. nasutus and iV. durus and som others, the interiör eggs develop first as a 

 rule, and are of such irregular forms that they seem to form one compact mäss in 

 which the nuclei are inbedded. 



But in the same species at the same time Ave also find ovaries of the well-known 

 old form, sometimes with one, sometimes also with two or more ripe eggs. In many 

 instances fine muscles or ligaments are seen to connect the ovary with the body-wall. 



In N- falciformis we invariably ineet with two ripe eggs in each ovary. M. pri- 

 ■mcevus has compact ovaries, scarcely lobated at all. In the nearly allied form M. mi- 

 rabilis the ovaries are more or less lobated, and the eggs were very often in different 

 stages of development in the different lobes. 



Receptacle. 



The receptacle in the fourth setigerous segment furnishes no generic characters of 

 value, but in distinguishing the different species from each other I consider its form 

 etc. of the greatest importance. In Enchytrcms and its subgenera Ave meet Avith t.AVo 

 distinct forms of receptacles, a more imperfect one and one higher developed. 



In its loAvest stage of development the receptacle consists. of a single tube, one 

 end of Avhich is affixed to the body Avall or rather opens betAveen the third and fourth 

 segments, the other end on the contrary is affixed to the intestine in the fourth seg- 

 ment. We find such a primitive form of a receptacle in all the three different genera, 

 and in species of no near relationship. The species alluded to are: Mesenchytr. falci- 

 formis, Archienchytr. Levinseni and tenellus and Neoenchytr. fenestratus. The recep- 

 tacles of the three last ones resemble each other very much and are hardly distin- 

 guishable by any thing else than their relative Avidth and length. 



