DESCRIPTIONS OF GENERA AND SPECIES 609 



to each segment. All these various sacs, which together constitute the sperm-receiving 

 apparatus, communicate with the exterior by a short very thick-walled Bursa. The 

 whole system of cavities is filled with spermatozoa, presumably received from another 

 individual ; in P. magilensis and P. violaceus, at any rate, these spermatozoa are in the 

 form of ' sperm-ropes,' which are much like those of the Tubificidae. The mouth 

 of the oviduct just by its division into the two branches which go respectively to the 

 egg-sac and to the ovarian sac, was invariably plugged with bundles of spermatozoa, 

 not in the form of sperm-ropes. This appears to indicate that fertilization takes 

 place at this point; but whether the spermatozoa have worked their way up the 

 oviduct or have come down from the spermathecal sac is a question that requires 

 further study before it can be decided. 



Polytoreutus has but one pair of testes ; these, as is usually but not invariably 

 the case when only one pair is developed, lie in the eleventh segment. The sperm- 

 sacs have a very unusual form unusual, that is to say, for this family ; they 

 resemble those of many Geoscolicidae in their extraordinary length. In P. magilensis 

 the sperm-sacs reach from the eleventh to the sixtieth segment ; the anterior part of 

 the sacs generally consists of a narrow tube lying freely in the body cavity riot 

 suspended in any way to neighbouring viscera ; from the thirtieth segment onwards 

 the sperm-sacs are thicker walled and sacculate, being constricted at the septa. 



The sperm-ducts are as in many Eudrilidae widened, just before they open into 

 the coelom by the funnel. 



The spermiducal glands are very long; in P. magilensis they extend through 

 about sixteen segments ; in P. coeruleus MICHAELSEN figures and describes a series 

 of regular short paired diverticula ; in P. magilensis they are sacculate. The five 

 species of the genus can be distinguished by the shape of the spermathecal sac. 



(i) Polytoreutus coeruleus, MICHAELSEN. 

 P. coeruleus, MICHAELSEN, JB. Hamb. wiss. Anst., vii, 1890, p. 24. 



Definition. Length, 140 mm.; breadth, 4 mm.; number of segments, 200. Clitellum, 

 XIII-XVIII. Spermathecal sac with two pairs of lateral diverticula, one in front of, 

 and one lehind the male pore. Hab. Makakalla, Korogice, M/tonda, E. Africa. 



This species (described by MICHAELSEN in two papers 6, 12) appears to occur in four 

 varieties, distinguished by the position of the male pores and that of certain papillae. 

 These differences are as follows : 



