194 MB. r. E. beddaud oisr the structure [Mar. 5, 



parts of the spermiclucal gland is rendered stronger by some 

 external strands of muscle, which run across the line of junction 

 and tie both parts to each other. These are shown in the accom- 

 panying drawing (text-fig. 53, p. 193). These strands of muscle, 

 which are accompanied by blood-vessels, can be seen to spring fan- 

 shaped to be detached from the walls of the spermiducal gland 

 posteriorly. Their general appearance is not unlike that of the 

 muscles which accompany the penial setae in those earthworms 

 which possess them. In the present genus such setae do not occur, 

 and it would be interesting to know whether their muscles have 

 remained and have been utilized for the extra strengthening of the 

 muscular spermiducal glands. The posterior region of the glands 

 is slightly and irregularly sacculated ; its walls are thick and chiefly 

 glandular. The single sperm-duct crosses over the terminal heart- 

 shaped portion of the spermiducal gland, and is at once lost in the 

 wall of the narrow distal portion. The two spermiducal glands 

 open posteriorly into the nearly circular terminal bursa. The latter 

 is of course overlain by the spermathecal sac ; its walls are very 

 thick and muscular. 



Spermathecal sac. — The species of the genus Polytoreutus are 

 mainly to be distinguished from each other by the form of the 

 very variable spermathecal sac. The present species, as is the 

 case with all the others, cau be defined by this structural feature 

 alone. The sac extends as usual from just behind the last thick- 

 ened septum to its orifice on to the exterior just behind the bursa 

 copulatrix. It dips down sharply behind the last-mentioned 

 structure. The sac therefore occupies rather more than 7 seg- 

 ments; it is some 9 mm. in length. The median spermathecal sac 

 lies of course below the nerve-cord ; it is entirely single through- 

 out its course and is not divided into right and left nearly 

 independent halves as in P. magilensis. The general appearance of 

 the spermathecal sac will be quite obvious from the accompanying 

 drawing (text-fig. 53, p. 193). As is the case with other species 

 of this genus, the median sac is furnished with lateral diverticula. 



The anterior end of the sac is provided with two long diver- 

 ticula of cylindrical form, each one of which is, when fully 

 extended, quite as long as the unpaired median sac. They touch 

 each other above the intestine, but they are not fused at that 

 point. The posterior pair of diverticula arise from the median sac 

 just before its opening on to the exterior. They are distinctly 

 shorter than the anterior pair of di\erticula, but more swollen. 

 The drawing also illustrates the relations of the oviduct, egg-sac. 

 and egg-tube to the spermathecal sac. It will be noticed that the 

 latter opens into the neck of the anterior diverticulum, close to its 

 junction with the median unpaired spermathecal sac. The oviduct 

 is long and but slightly curved. The chamber into which the 

 oviduct opens (" Eitrichterblase ") is of about the same size as, 

 and is situated exactly opposite to, the egg-sac (receptaculum 

 ovorum). 



The species may be thus defined ; 



