HORN EXPEDITION—ZOOLOGY. APPENDIX. 
419 
Clitelluni well marked, extending over segment!? 13-17, and including the 
anterior half of 18. Incomplete in the median ventral line in segments 17 and 18. 
Seta? very small and inconspicuous. The two of each pair very close together. 
Regularly arranged. 
Male pores on segment 18, slightly ventral to the level of the inner pair of 
setie of each side. The ventral pair of setm on each side absent on the 18th 
segment. 
Openings of prostate glands on segments 17 and 19, at the same level as the 
male pores. Penial setie present. Long, thin, and without ornament. 
Oviduct pores on segment 14, just in front of and external to the level of the 
inner pair of setie of each side. 
Spermathecal pores. Two pairs between segments 7 and 8, 8 and 9 at the 
level of the inner pair of setai of each side. 
Accessoi’y copulatory structures. Not usually well developed. Elliptical 
tumid patches may be present at the level of the inner pair of seta? of each side, 
between some or all of segments 17 and 18, 18 and 19, 19 and 20, 21 and 22. 
Dorsal pores. Present behind the clitellum. 
Alimentary canal. Gizzard in segment 5. No calciferous glands or even 
swollen vascular pouches on the oesophagus. Large intestine commencing in 
segment 17. 
Circulatory system. Single dorsal blood vessel. Hearts in segments 5-13 
inclusive. A well-marked lateral blood vessel on each side of the gizzard. 
Excretory system meganeploric. Regularly arranged. Nephridiopores just in 
front of the inner pairs of setm on each side. Peptonephridia present. 
Reproductive system. Two pairs of testes, one each in segments 10 and 11, 
into which also the rosettes open. 
Prostates tubular, the anterior being larger than the posterior, and extending 
through segments 17-20; the posterior lying in segments 19 and 20. Each is 
supported by a double muscle slip, extending backwards and upwards into 
segment 22. 
Sperm sacs, two pairs, racemose, one attached to the posterior wall of segment 
9, the other to the anterior wall of segment 12. 
