KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 15. NIO 7. 1 1 



Subgenus III. NEOBNCHYTR/EUS n. 



The spermatozoa, when they enter the efferent duet are always free. 



The posterior margin of the supra-cesophagial ganglion is always convex. 



The tube of the efferent duet is always long and narrow as in the preceding 

 subgenus. 



Leydig, in Tafeln zur vergl. Anatomie, has already indicated the importance of 

 the supra-oesophagial ganglion as characteristic of a species, and Ratzel distinguishes 

 two species from each other through that characteristic, and points out its value. As 

 such it was assuredly very good, at a time, when in the whole genus Enchytrceus were 

 known only three or four species, but at present, when five or six times that number 

 are more or less sufficiently described, it can hardly any morc be considered as a 

 specilic characteristic. The particular shape, however, of the said ganglion is always 

 of great importance, and when describing the different species I have always endea- 

 voured to give a correct drawing of the same. 



As other important characteristics of the species I consider the size and shape of 

 the receptaele, and the form of the segmental organs. 



The form of the efferent duet of the ovaries and the testes is also of some 

 signiheance, but considering the variation of these organs in one and the same species, 

 I do not attach to them a very high value as characteristics of the species. In the 

 subgenus Mesenehytrceus alone the shape of the efferent duet is of real importance. 



The lymphatic cells, the perigastric bodies furnish characteristics of value, not 

 so much for the separation of species as for the distinction of whole tribes. They do 

 not occur in all species, and are not ecpially numerous in different individuals of the 

 same species. 



The old way of distinguishing species by external characters alone I have now 

 entirely given up, being satisfied that in this family no external characters whatever 

 will in any way suffice even to distinguish two not very closely allied species. Some 

 small external differences, of course, exist, but the most we can say about them is, 

 that they will sometimes aid us in separating the different species, if we previously 

 know them to be different, dissection being always necessary for deciding to what 

 subgenus and species they may belong. 



Mesenchytraeus n. 



A. The tube of the efferent duet is very short and not differentiated from the 

 vesiele of said organ : M. primcevus n. 



B. The tube of the efferent duet is six to eight times longer than the vesiele 

 and well differentiated. 



B'. The receptaele is large and turret-like and furnished with follicles near 

 the base for the reception of the spermatozoa: M. mirabilis n. 



B". The receptaele consists of a simple tube, no follicles for the spermatozoa: 



M. falciformis n. 



