CHAETOPODA 



149 



which are very constant in position, being with hardly an ex- 

 ception in the 13 th segment. In Uudrilus (Fig. 94) the ovary 

 is enclosed in a muscular sheath. The ciliated oviduct passes 

 through the sheath, and ends in a funnel-shaped mouth in the 

 ovary. The muscular sheaths of the oviduct and ovary are 



Fig. 94. — Female reproductive apparatus of JSu- 

 drilus. On the right side the spermatheca has 

 been cut away to show the contorted oviduct, 4. 

 1. Ovary. 2. Spermatheca. 



3. Gland opening into conjoined duct of sper- 



matheca and oviduct. After Beddard. 



4. Oviduct. 



continuous. The oviduct is convoluted, and opens to the ex- 

 terior on the 14th seginent, together with a spermatheca and 

 a small glandular body. The opening of the oviduct in Peri- 



FiG. 95. — Diagrams of various earth- 

 worms to illustrate external char- 

 acters. A, B, C, anterior segments 

 from the ventral surface. D, 

 hinder end of body of Urochaeta. 



A. Lumhricus ; 9 and 10, segments 



contain spermathecae, the ori- 

 fices of which are indicated ; 

 14, segment bears oviducal 

 pores ; 15, segment bears male 

 pores ; 32, 37, first and last 

 segments of the clitellum. 



B. Acanthodrilus ; 1, orifice of sper- 



mathecae ; 9 , oviducal pores ; 

 S, male pores. 



C. Perichaeta; the spermathecal pores 



are between segments 6 and 7, 

 7 and 8, and 8 and 9, the ovi- 

 ducal pore on the 14th, the male 

 pores on the 18th segment. 



In all the figures the nephiidial 

 pores are indicated by dots, the setae 

 by strokes. 



chaeta is single and median. The various positions of the 

 genital apertures, and their relations to the nephridia and setae 

 in various genera, are shown in Fig. 95. In the aquatic 

 Oligochaets the nephridia are not found in those segments 

 which lodge the reproductive organs and their ducts ; in 

 the terrestrial forms they coexist. Some of the setae in the 



