KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 15. N:0 7. 39 



lobes and its segmental organs are of the same enormous development as those of the 

 last mentioned species. 



In M. falciformis there exists merely a träce of lobation and the middle lobe is 

 but slightly divided in the margin. 



The middle lobe of the other subgenera and their species varies very little and 

 the slight variations to which it is subject can be better seen by studying the fi- 

 gures than by any lengthy and detailed descriptions. 



The outer lobe or tube varies to same extent. It is generally long and narroAv, 

 its length being that of the middle lobe. In A. nasutus, N. durus and Ratzeli it is 

 very long and narrow, and in the latter two species about twice as long as the middle 

 lobe. In N. Stuxbergi and Vejdovskyi, two species resembling each other in many points, 

 the outer tube is of the same length as the middle lobe, thick, cylindrical, and very 

 unlike those of the other known species. 



In N. callosus on the contrary the tube is five times shorter than the middle 

 lobe. 



In M. primcevus and mirabilis the outer tube is wedgeshaped and in the former 

 species it is very short. 



The inner tube varies very much in size. The longest and narrowest one is 

 found in M. primcevus and the broadest and largest in N. callosus, durus and 

 Ratzeli. In A. gemmatus the tube is broad, nearly as broad as the middle lobe and 

 also nearly of the same length, which characterizes the organ very much. In A. tenellus 

 and Levinseni it is very short or of about a third of the length of the middle lobe 

 and the opening is surrounded by a heavy lip. In N. Stuxbergi and Vejdovslcyi the 

 tube is also very short and in both species, as well as the whole organ, of almost ex- 

 actly the same shape. The inner orifice is here not surrounded by a swelled lip. 



The glandular matrix surrounding the tube contains sometimes a few plainly dis- 

 cernible cell-nuclei, generally crowded round the interiör and outer orifices: the}' are 

 most plainly visible in M. mirabilis, A. profugus and in a few others. In the last men- 

 tioned species they are also dispersed in the matrix of the middle lobe. 



The winding of the lumen or the tube in the different lobes are very difficult to 

 follow, only in the species of Neoenchytrams are the windings easily seen. The draw- 

 ings are as exact as possible. 



However slight the variations of the segmental organs are, they nevertheless fur- 

 nish good characteristics for the distinction of the species and the diagnoses are not 

 exhaustive unless they also comprise the descriptions of the shape of the segmental 

 organs. 



Perigastrie bodies. 



It seems to be generally understood that the perigastrie cells are always free and 

 floating, that they exist in all species, and are of an appearance peculiar enough to 

 characterize the species. As far as my experience goes this however is not the case. 

 They do not exist in every species, and are in many species of exactly the same shape 



