[31] OLIGOCH^TOLOGICAL RESEARCHES. 909 



ments, from the eleventh to the fourteenth, and in Ilyodrilus fragilis we 

 find them not only in the three first segments behind the cingulum, but 

 also in front of the same. 



In Spirosperma a large single testis is found in the ninth setigerous 

 segment, occupying that segment and a part of the next or the tenth 

 segment. But also in the eleventh, twelfth, and thirteenth segments 

 are found testes, but here not a single one, but one pair in each segment, 

 or, all in all, seven testes. 



In Psammoryctes, according to Vejdovsky*, testes are as well found in 

 the eighth setigerous segment as in the eleventh, extending as far back 

 as to the twentieth segment. The testes in this species seem to be single. 



In LvmnodriliLs we find the testes generally behind the cingulum, 

 except in the two species described by ClaparMe, viz, L. Hoffmeisteri 

 and L. Udelceniianus, both of which have testes, one in front of the 

 cingulum, or in the eighth segment, and one or two behind the cingu- 

 lum, or in the tenth, eleventh, and twelfth setigerous segments. 



In Limnodrilus Silvani we find one pair of testes in the eighth seg- 

 ment, and one single continuous testis behind the cingulum in the 

 eleventh to the fourteenth setigerous segment. In Limnodrilus ornatus, 

 as in most of the species, we find testes only behind the cingulum. 



In Gamptodrilus igneus we find one testis extending through the 

 eleventh to fourteenth setigerous segment, and one through the fif- 

 teenth and sixteenth ditto. In Gamptodrilus corallinus the testes form 

 a continuous body from the seventh to the fifteenth setigerous segment. 



In HemituM/ex we also find a continuous testis extending from the 

 eleventh to the sixteenth setigerous segment. iNTone in front of the cin- 

 gulum. 



The exact number and position of the testes are oftentimes difiacult 

 to ascertain, because the different testes seem, at least apparently, to 

 connect with each other, and every attempt to dissect them will often 

 prove unsuccessful on account of their delicate structure. The exact 

 number and position of the testes is also of less importance as a char- 

 acteristic of the species. The most important point is to know if a testis 

 is found in front or behind the cingulum, or if the testis is" single or 

 occurs in pair. 



The single testis is the most common one. In pair tl^ testes are 

 found only in three species, viz : 



a. In front of the cingulum in Telmatodrilus and Limnodrilus Silvani. 



b. Behind the cingulum in Spirosperma ferox. 



The testes in all the above species are not much lobed, but almost 

 entire or amorphous. Testes similar to those of Enchytrmus profugus 

 and nervosus and Fachydrilus Glaparede are not yet observed in Tubi- 

 ficini. 



OVARIES. 



The ovaries in Tubijioidw resemble to a great extent those met with in 

 Encliytrmidce. They are mostly found in the tenth setigerous segment, 

 *Uel»er Psanimoryctes, p.l43. 



