[37] OLIGOCH^TOLOGICAL RESEARCHES. 915 



the most primitive and simplest oviduct was found in Tehnatodrilus, 

 and that it here consisted merely of a fold of the body wall. Investi- 

 gation of a larger number of species, however, has led me to (consider- 

 ably change my former views, and the discovery of a minute penis 

 sheath even in this species is evidence that the penis and oviduct here 

 are just as complicated as in the subfamily of TuMficinL 



The oviduct of Telmdtodrilus (Fig. 1, e, ovd.) consists of a large, 

 heavy, opacous, muscular sack, inclosing the whole of the interior 

 penis. One end of the same is attached to the body wall all round the 

 genital porus. The other end is free, but its aperture is not clearly 

 defined, and so surrounded by muscles that all observation is very diffi- 

 cult. The oviduct in this species is single. 



In Tubificini the oviduct always consists of a more or less sack-like 

 organ, extending from the genital porus towards the interior of the 

 body. In the species of Tubifex this organ is broad and rounded; in 

 Camptodrihis elongated and narrow. In Limnodrilus and GdmptodrUm 

 the interior aperture of the oviduct is extremely narrow, inclosing the 

 atrium tightly, at least when the animal is dead, and the most careful 

 observation is needed to detect it at all. In Remituhifex, Tubifex, Spi- 

 rosperma, and also in some species of Ilyodrilus, this aperture, however, 

 is wide and easily detectable. In many instances the oviduct is funnel- 

 shaped, and sometimes the widest opening turned toward the body wall, 

 a-s in Ilyodrilus sodalis. In other species, such as Hemitubifex and Ilyo- 

 drilus fragilis, the contrary takes place. In Ilyodrilus sodalis the mem- 

 brane of the oviduct is full of very minute spicula irregularly distri- 

 buted. Such spicula are also found in the oviduct of Psammoryctes, 

 but here only at the upper end of the organ where it touches the atrium 

 proper. The exterior oviduct is more or less chitinous, but also muscu- 

 lar, as in Spirosperma and Ilyodrilus Ferrierii. 



An interior sheath between the oviduct and the penis sheath, or what 

 I have designated as a double oviduct, is found in many species. We 

 find it thus in all the species of Limnodrilus except in L. ornatus. In 

 Gamptodrilus we find it only in G. spiralis, but not in any other species 

 of the genus. The oviduct is also double in Hemitubifex, Tubifex, and 

 Ilyodrilus Perrierii. This interior sheath of the oviduct is free at both 

 ends, and not directly connected with the body wall. In Gamptodrilus 

 spiralis, Limnodrilus alpestris, and L. monticola this interior sheath is 

 chitinous, and resembles closely the form of the penis sheath, which it 

 incloses. In Limnodrilus Steigerwaldii it is decidedly muscular, com- 

 posed of numerous layers of concentric muscles of apparently great 

 strength. In Hemitubifex the exterior and interior sheaths of the ovi- 

 duct are exactly of the same form as the penis sheath, or funnel-shaped, 

 but of course of different sizes, as the one is inclosing the other. 



The exterior oviduct is always more or less surrounded by muscles. 

 Generally these are longitudinal, and attached either to the exterior 

 surface of the oviduct, and in this case of a greater number, or to the 



